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9L0-063 Mac OS X Troubleshooting 10.7

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9L0-063 exam Dumps Source : Mac OS X Troubleshooting 10.7

Test Code : 9L0-063
Test cognomen : Mac OS X Troubleshooting 10.7
Vendor cognomen : Apple
: 65 actual Questions

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Apple Apple Mac OS X

how to Revisit each version of Mac OS X from your Browser | killexams.com actual Questions and Pass4sure dumps

The Aqua GUI in Apple’s operating techniques has gone through a Amazing evolution because March of 2000, when it discovered its course into OS X 10.0, and you might possibly breathe stunned at simply how distinctive every thing appears now. because of the newly launched Aqua Screenshot Library, which you can revisit each version of OS X (and macOS) during the years and view the gradual evolution of Apple’s operating equipment—all out of your browser.

The huge gallery is the latest travail by means of 512 Pixels, an internet library that makes an attempt to hold tabs on utter things Apple (including the Mac’s many wallpapers). The Aqua Screenshot Library, as creator Stephen Hackett notes, provides a complete look to breathe at the history of Apple’s operating programs, which covers its start to from bulkier CRTs to compact, LED-backlit displays; Apple’s quite a lot of font alterations over the years; and Apple’s stream from disc-based operating techniques to (free) digital downloads.

Let’s boost a glance at some of these needful Mac milestones.

Mac OS X 10.0 (“Cheetah”)

March 24, 2001, marked the first legitimate unlock of the Mac OS X operating equipment, following a public beta the yr earlier than. Hackett notes that its 128MB recollection requirement became “more than most Mac users had of their programs on the time.” This result in many complaints in regards to the OS’s slack efficiency and extreme useful resource demand. The Cheetah interface retained the pin-striped menu and window design from the beta, but it begun the feline-based mostly naming vogue which would last as much as edition 10.eight, “Mountain Lion.”

Mac OS X Leopard (10.5)

The closing months of 2007 brought some huge changes to OS X. The free up of Leopard saw Aqua boost on a a whole lot greater streamlined appear, with utter home windows now defaulting to a single, elementary grey design, as neatly because the debut of a redesigned Finder tool. prior to this, discrete apps—and diverse types of OS X—had assorted UI designs (for better or worse). With Leopard’s free up, OS X started to explore more uniform. most importantly, it turned into the primary edition to encompass those rad, house-primarily based backgrounds.

OS X Mountain Lion (10.8)

Mountain Lion become the primary version of OS X to gain after Steve Jobs’ dying, and it concentrated on aligning Mac computers with the late CEO’s different needful contribution to the tech business: the iPhone. The 2011 OS X update, Mac OS X Lion (10.7), kicked off Apple’s merging of iOS aesthetics into OS X, and the company doubled down with Mountain Lion. equipment and applications occupy been renamed after iOS facets, and Apple brought some little visible and input changes to bridge the two working programs even nearer collectively—in vogue, at least.

OS X Mavericks (10.9)

Mavericks became an gigantic commerce pivot for Apple, because it become the first version of the OS the company released for gratis, offered to clients as an upgrade by the consume of the App redeem in October 2013. Apple hasn’t long gone returned to paid operating systems considering that—happily. Mavericks was additionally the primary version of OS X to originate consume of non-pussycat nomenclature. It furthermore ditched the galactic history theme for California landscapes, which they can utter correspond become an gigantic blunder. right?

macOS Sierra (10.12)

edition 10.12 of Apple’s operating equipment for the Mac is most is extraordinary for its large rebranding. Apple dropped the “OS X” identify thoroughly in this free up, as a substitute calling its operating gadget “macOS” to align it the business’s working systems on different structures: iOS, watchOS, and tvOS. 

browsing the Aqua Screenshot Library is a enjoyable approach to descry just how far macOS has come, peculiarly to descry how Apple’s design priorities exchange between the fundamental releases. however, the Aqua Screenshot gallery is just one of 512 Pixels’ many initiatives to try. originate inescapable to poke across the other Apple-themed collections Hackett has assembled over the years, too, including the astonishing 512 Pixels YouTube channel.


OS X/macOS now older than traditional Mac OS | killexams.com actual Questions and Pass4sure dumps

Older readers could nonetheless suffer in intelligence when Macs made the transition to OS X, more these days rebranded to macOS. but when you nonetheless benevolent of suppose of that because the ‘new’ OS, as of these days it’s in reality now been round for longer than utter of the preceding models – collectively and colloquially called basic Mac OS …

Jason Snell marked the occasion in a blog attach up the day before today.

today marks 17 years, one month, and 29 days on account that Mac OS X 10.0 changed into launched on March 24, 2001. That’s a surprisingly unusual quantity—6,269 days—however additionally happens to breathe the exact size of time between January 24, 1984 (the launch of the long-established Macintosh) and March 24, 2001.

In other words, nowadays the Mac’s 2nd working gadget period, powered by Mac OS X (now macOS) has been in existence provided that the first era was.

As he notes, it does reckon just a puny on the course you measure these things.

There became a Mac OS X public beta. The funeral for Mac OS 9 wasn’t held except 2002. basic Mode persisted to characteristic within Mac OS X except it became removed in Mac OS X 10.5 Leopard.

So for beta users, the milestone may additionally had been passed ages lower back, and for those that held onto Mac OS 9 for some time after OS X launched, it can not yet occupy arrived.

Early models of the Macintosh equipment utility had no dependable identify, with Apple referring most effective to Macintosh Toolbox ROM and the system Folder. It only became Macintosh gadget utility in 1987, with what was then referred to as system 5. Apple rebranded it to Mac OS in 1996, at equipment 7.6.

As to the long run, Snell says that he doesn’t descry a ‘seismic’ shift any time soon, more a gradual raise within the borrowing from iOS. however he does renowned that a fresh chip could descry the system revolve up in utter places again.

there was persisted hypothesis about Apple switching from Intel to ARM chips for future Macs, with one recent file suggesting it may ensue as quickly as 2020. I gave my very own view on that conception, concluding that the date may appear unlikely, but that it's coming quickly.

that you can download utter the default wallpapers in 5K from 512 Pixels.

by means of Daring Fireball. image: 512 Pixels

try 9to5Mac on YouTube for more Apple information:


listed here are the 13 most useful Mac shortcuts so that you can aid you Do every thing quicker | killexams.com actual Questions and Pass4sure dumps

apple white macbookmaster your MacBook. Mustafa Quraishi/AP

Apple's MacOS may look simple — however's an absolute powerhouse in case you comprehend how to consume it.

one of the easiest the course to find probably the most of out of Apple's laptop working device are hidden in undeniable sight: Keyboard shortcuts.

Flick between purposes and tabs. boost screenshots. best-tune settings. knowing the appropriate keyboard shortcuts will store a 2nd here and there — and over the course of per week, or a month, or a 12 months, it provides up dramatically.

if you are sentiment adventurous, Apple lists utter of its Mac keyboard shortcuts here.

here are 13 of the most advantageous keyboard shortcuts with a view to redeem you time on the puny things so you can focus on the large things:

(Max Slater-Robins contributed to an past edition of this article.)


9L0-063 Mac OS X Troubleshooting 10.7

Study usher Prepared by Killexams.com Apple Dumps Experts


Killexams.com 9L0-063 Dumps and actual Questions

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9L0-063 exam Dumps Source : Mac OS X Troubleshooting 10.7

Test Code : 9L0-063
Test cognomen : Mac OS X Troubleshooting 10.7
Vendor cognomen : Apple
: 65 actual Questions

worked difficult on 9L0-063 books, however the entire component occupy become on this test manual.
I got a advantageous result with this bundle. Very advantageous quality, questions are accurate and I got most of them on the exam. After I occupy passed it, I recommended killexams.com to my colleagues, and everyone passed their exams, too (some of them took Cisco exams, others did Microsoft, VMware, etc). I occupy not heard a contaminated review of killexams.com, so this must breathe the best IT training you can currently find online.


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Mac OS X Troubleshooting 10.7

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Inside Mac OS X 10.7 Lion: fresh Wi-Fi Diagnostics appliance | killexams.com actual questions and Pass4sure dumps

 

Feature

Apple has added a fresh Wi-Fi Diagnostics utility to monitor the performance of wireless networks, record events, capture raw network frames, and log diagnostic data that can breathe sent to Apple by users for troubleshooting.The fresh app is in the hidden /System/Library/CoreServices folder, where Mac OS X stores a variety of utility apps that are integrated into the Mac desktop, including the Dock, Finder, Software Update, and Archive Utility.

Users can launch the appliance by Option clicking on the Wi-Fi Menu Bar icon, which then presents an otherwise hidden "Open Wi-Fi Diagnostics" option (below).

After opening, the appliance presents options to Monitor Performance, Record Events, Capture Raw Frames, or revolve on Debug Logs. A Learn More button outlines what these options Do in a drop down sheet (below).

Monitor Performance works similar to AirPort Utility's Wireless Clients graphing feature, but provides a more circumstantial presentation of signal and noise for the client, rather than tracking every active client on a given ground station. It can furthermore Report the collected data to Apple for consume in troubleshooting issues.

Other options log events or capture raw frame data in the background to a temporary .pcap (packet capture) file, which can similarly breathe reported to Apple for troubleshooting help.

Also noticeably fresh and different in Mac OS X Lion is network setup for 802.1x security. Formerly, users could manually enter settings or install a profile the automatically configured the settings. In Lion, Apple informs users that their network administrator will deliver a configuration profile (below).

Apple created configuration profiles for iOS along with a system site administrators can consume to roll out initial settings and subsequent updates to their users. In Lion Server, the same infrastructure can breathe used to remotely deliver network configuration files that automate the management of Macs just dote iOS devices.


How to Create a Bootable Mac OS X USB Disk | killexams.com actual questions and Pass4sure dumps

This article will allow you to learn the necessary steps for creating your own bootable Mac OS X Leopard (or Lion) image on a USB recollection stick. This might breathe needed if your Mac needs a reinstall or a “Repair Disk” procedure and it has problems reading the bundled Install disc. To consume this tutorial an 8 GB or larger USB stick, a second Mac computer with a working SuperDrive or a Mac OS X Install disc DMG file will breathe needed.

If you ever had problems with your Mac OS X installation you know that the first thing you should Do is to check the startup volume using Disk Utility.

After the check has ended and, if the errors exceed a inescapable plane of seriousness, the Disk Utility application will require you to restart your Mac and consume its Mac OS X Install disc counterpart.

Other users may occupy to reinstall OS X altogether, but will find, or already know, that their SuperDrive (a CD/DVD reader and write combo drive) is not functioning properly and it will not breathe able to read the Install disc.

Although this might happen to Mac OS X Leopard users due to faulty hardware, the vast majority of problematic SuperDrives will breathe encountered inside Snow Leopard running Macs.

This is due to the updated SuperDrive firmware included in either the Install disc or the software updates one has to install to gain the latest version of OS X, namely 10.6.6.

This can breathe fixed by flashing the SuperDrive’s stock firmware using free command line tools that one can find for free online (I will write about this process also, but at a later time because this article only focuses on allowing you to create your own alternative USB boot disc).

If you are reading this last bit of information with skepticism, than you should know that it happened to me too. Despite utter my tries to originate it travail properly, the SuperDrive kept on munching any inserted DVDs and just popped them out in about twenty seconds.

The workaround to this issue was to create my own Leopard bootable USB recollection stick. I am not suggesting a Snow Leopard bootable stick mainly because there are lots of users that occupy decided to buy the cheaper, Upgrade version, which I occupy not tested and, therefore, I’m not certain if it will travail properly once written to a USB disk.

And now, here are the exact steps you should ensue in order to obtain a fully bootable Leopard (or Lion) Install disc.

Step 1 (If you already occupy the Leopard install disc DMG file you can skip to Step 2)

Launch Disk Utility (you can find it inside /Applications/Utilities). Here select the Leopard Install disc in the list of drives on the left and click on the fresh Image menu entry at the top of the window. A redeem message will appear where you will occupy to select the Desktop as a destination.

Step 2

After Disk Utility has finished creating the Leopard DMG, insert your USB stick and delete utter data and reformat the disk. To Do this select the USB in the list of drives on the left and, after clicking on the delete tab on the birthright side of the window, pick the Mac OS Extended (Journaled) format and click the delete button beneath.

Step 3

After the USB has been reformatted, download the SuperDuper app from HERE and launch it. Once SuperDuper starts, you will only occupy to select the DMG in the Copy drop-down menu, your USB recollection stick on the birthright and hit the “Copy Now” button.

One can furthermore consume Disk Utility for this assignment but creating a bootable USB stick failed 2 out 4 times when copying the DMG to the stick (with the exact same settings each time). Creating the bootable stick using SuperDuper proved to breathe the impeccable course to Do it because it worked each of the 4 times I tested it.

The steps above can furthermore breathe used to create a bootable Mac OS X Lion USB by using the InstallESD.dmg image you can find inside the Lion installer (named “Install Mac OS X Lion.app”) downloaded from the Mac App Store in the /Applications folder.

To locate the InstallESD.dmg birthright click the Lion installer, select the “Show Package Contents” entry, fade inside the “Contents” folder, and from there into the “SharedSupport” folder. Inside this folder you can find the InstallESD.dmg you can consume to create your own bootable Mac OS X Lion USB stick. To Do so, fade to the third step described above and consume the InstallESD.dmg as the DMG to breathe copied to your USB disc.

That’s it! Once the process ends you will occupy a fully bootable Leopard (or Lion) USB disk that you can consume as an alternative to the Apple’s DVD Install disc that comes bundled with utter Macs.

To consume your newly created bootable disk you will occupy to restart the Mac, press and hold the OPTION key until the Startup Manager appears. Here, select the Mac OS X Install disk using your keyboard arrows and press recur to start from the selected drive.

If you occupy any questions or any problems while following the above steps, leave a observation and I will find back to you with an retort as soon as possible.

[Update 1] Added the minimum USB stick size needed at the beginning of the article and Install Mac OS X Lion.app's location.


Mac OS X 10.7 Lion: the Ars Technica review | killexams.com actual questions and Pass4sure dumps

Mac OS X 10.7 Lion: the Ars Technica review reader comments 401 with 262 posters participating, including chronicle author Share this story
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  • Mac OS X 10.7 was first shown to the public in October 2010. The presentation was understated, especially compared to the bold rhetoric that accompanied the launches of the iPhone ("Apple reinvents the phone") and the iPad ("a magical and revolutionary device at an unbelievable price"). Instead, Steve Jobs simply called the fresh operating system "a sneak peek at where we're going with Mac OS X."

    Behind Jobs, the screen listed the seven previous major releases of Mac OS X: Cheetah, Puma, Jaguar, Panther, Tiger, Leopard, and Snow Leopard. Such brief retrospectives are de rigueur at major Mac OS X announcements, but long-time Apple watchers might occupy felt a slight tingle this time. The public "big cat" branding for Mac OS X only began with Jaguar; code names for the two earlier versions were not well known outside the developer community and were certainly not allotment of Apple's official marketing message for those releases. Why bring the cat theme back to the forefront now?

    Want an eBook or PDF copy? support Ars and it's yours.

    The retort came on the next slide. The next major release of Mac OS X would breathe called Lion. Jobs didn't originate a large deal out of it; Lion's just another large cat name, right? Within seconds, they were on to the next slide, where Jobs was pitching the fresh release's message: not "king of the jungle" or "the biggest large cat," but the "back to the Mac" theme underlying the entire event. Mac OS X had spawned iOS, and now Apple was bringing innovations from its mobile operating system back to Mac OS X.

    Apple had advantageous understanding to bashful away from presenting Lion as the pinnacle that its cognomen implies. The last two major releases of Mac OS X were both profoundly shaped by the meteoric surge of their younger sibling, iOS.

    Steve Jobs presents the first seven releases of Mac OS X in a slightly unusual formatSteve Jobs presents the first seven releases of Mac OS X in a slightly unusual format

    Leopard arrived later than expected, and in the same year that the iPhone was introduced. Its successor, Snow Leopard, famously arrived with Your browser does not support the audio element. Click here to listen

    no fresh features , concentrating instead on internal enhancements and bug fixes. Despite credible official explanations, it was hard to shake the sentiment that Apple's burgeoning mobile platform was stealing resources—not to mention the spotlight—from the Mac.

    In this context, the cognomen Lion starts to boost on darker connotations. At the very least, it seems dote the discontinuance of the large cat branding—after all, where can you fade after Lion? Is this process of taking the best from iOS and bringing it back to the Mac platform just the first side of a complete assimilation? Is Lion the discontinuance of the line for Mac OS X itself?

    Let's attach aside the pessimistic prognostication for now and consider Lion as a product, not a portent. Apple pegs Lion at 250+ fresh features, which doesn't quite match the 300 touted for Leopard, but I guess it utter depends on what you consider a "feature" (and what that "+" is hypothetical to mean). Still, this is the most significant release of Mac OS X in many years—perhaps the most significant release ever. Though the number of fresh APIs introduced in Lion may drop short of the landmark Tiger and Leopard releases, the most needful changes in Lion are radical accelerations of past trends. Apple appears tired of dragging people kicking and screaming into the future; with Lion, it has simply decided to leave without us.

    Table of Contents
  • Installation
  • Reconsidering fundamentals
  • Lion's fresh look
  • Scroll bars
  • Window resizing
  • Animation
  • Here's to the crazy ones
  • Window management
  • Application management
  • Document model
  • Process model
  • The pitch
  • The reality
  • Internals
  • Security
  • Sandboxing
  • Privilege separation
  • Automatic Reference Counting
  • Enter (and exit) garbage collection
  • Cocoa recollection management
  • Enter ARC
  • ARC versus garbage collection
  • ARC versus the world
  • The condition of the file system
  • What's wrong with HFS+
  • File system changes in Lion
  • File system future
  • Document revisions
  • Resolution independence
  • Applications
  • The Finder
  • Mail
  • Safari
  • Grab bag
  • System Preferences
  • Auto-correction
  • Mobile Time Machine
  • Lock screen
  • Emoji
  • Terminal
  • About This Mac
  • Recommendations
  • Conclusion
  • A brief note on branding: on Apple's website and in some—but not all—marketing materials, Apple refers to its fresh Mac operating system as "OS X Lion." This may well revolve out to breathe the cognomen going forward, but given the current condition of confusion and my own stubborn nostalgia, I'm going to summon it "Mac OS X" throughout this review. Indulge me.

    Installation

    Lion's system requirements don't disagree much from Snow Leopard's. You quiet requisite an Intel-based Mac, though this time it must furthermore breathe 64-bit. The last 32-bit Intel Mac was discontinued in August of 2007; Apple chose a similar four-year cut-off for dropping PowerPC support, with minimal customer backlash. Time marches on.

    But sometimes time marches on a bit too fast. Though this is the second version of Mac OS X that doesn't support PowerPC processors, this is the first version that won't flee PowerPC applications. In Snow Leopard, the Rosetta translation engine allowed PowerPC applications to run, and flee well, often faster than they ran on the (admittedly older) PowerPC Macs for which they were developed. Lion no longer includes Rosetta, even as an optional install.

    No one expects eternal support for PowerPC software, and any developer that doesn't yet occupy Intel-native versions of utter its applications is clearly not particularly dedicated to the Mac platform. Nevertheless, people quiet reckon on some PowerPC applications. For example, I occupy an dilapidated PowerPC version of Photoshop. Though Photoshop has long since gone Intel-native, it's an expensive upgrade for someone dote me who uses the program only rarely. The PowerPC version suits my needs just fine, but it won't flee at utter in Lion.

    Another common sample is Quicken 2007, quiet the most capable Mac version of Intuit's finance software, and quiet PowerPC-only. This is clearly Intuit's fault, not Apple's, but from a regular user's perspective, it's hard to understand why Apple would remove an existing, completed feature that helped so many people.

    In reality, every feature has some associated maintenance cost. This is perhaps even more suitable of a binary translation framework that may occupy abysmal hooks into the operating system. I'm willing to give Apple the capitalize of the doubt and assume that disentangling PowerPC-related code from the operating system once and for utter was needful enough to justify the customer inconvenience. But it quiet stings a little.

    The future shock continues with the purchase and installation process. Lion is the first version of Mac OS X to breathe distributed through Apple's recently introduced Mac App Store. In fact, the Mac App Store is the only Place where you can buy Lion.

    Apple's decision last year to sell its iLife and iWork applications through the Mac App Store was not unexpected, but the presence of Apple's professional photography application, Aperture, caught some people off guard—as did its greatly reduced cost ($80 vs. $200 for the boxed version).

    The developer preview releases of Lion were furthermore distributed through the Mac App Store. Apple's developer releases occupy been distributed digitally for many years now, but the switch from downloading disk images from Apple's developer website to "redeeming" promo codes and downloading fresh builds from the Mac App Store raised some eyebrows. When Apple announced that its fresh Final chop Pro X professional video editing application would—you guessed it—be distributed through the Mac App Store, and at a greatly reduced price, even the most dense Apple watchers started to find the hint.

    The Lion installer application iconThe Lion installer application icon

    And so they occupy Lion, priced at a mere $29 (the same as its "no fresh features" predecessor), available exclusively through the Mac App Store. It's an audacious move, yes, but not unexpected.

    Apple is so done with stamping bits onto plastic discs, putting the discs into cardboard boxes, putting those boxes onto trucks, planes, and boats, and shipping them utter over the world to retail stores or to mail-order resellers who will eventually attach those same boxes onto a different set of trucks, trains, and planes for final delivery to customers, who will then remove the disc, sling away the cardboard, and instruct their computers to extract the bits. No, from here on out, it's digital distribution utter the way. (This, I suppose, marks the discontinuance of my longstanding tradition of showing the product boxes or optical discs that Mac OS X ships on. Instead, you can descry the installer application icon on the right.)

    Lion is a large download and fleet network connections are quiet not ubiquitous. But fresh Macs will gain with Lion, so the most pertinent question is, how many people who strategy to upgrade an existing Mac to Lion don't occupy a fleet network connection? The class of people who execute OS upgrades probably has a higher penetration of high-speed Internet access than the universal population. I furthermore suspect that Apple retail stores may breathe willing to back out customers who just can't manage to download a 3.76GB installer in a reasonable amount of time.

    [Update: Macworld reports that there will, in fact, breathe a physical manifestation of Lion. Starting in August, Apple will sell Lion on a USB stick for $69. Apple has furthermore said that customers are welcome to bring their Macs to Apple retail stores for back buying and installing Lion.]

    In the meantime, if you're reading this, chances are advantageous that you occupy a fleet broadband connection; feel free to quit reading birthright now, launch the Mac App Store, and start your multi-gigabyte download before continuing. What you'll breathe rewarded with at the discontinuance is an icon in your Applications folder labeled "Install Mac OS X Lion." (See?)

    Once you occupy the installer application, you could (were you so inclined) dig into it (control-click, then account for Package Contents) and find the meaty center, a 3.74GB disk image (InstallESD.dmg, stored in the Contents/SharedSupport folder). You could then consume that disk image to, say, scorch a Lion installation DVD or create an emergency external boot disk.

    I doubt any of these things are officially supported by Apple, but the point is that there's nothing exotic about the Lion installer. dote utter past versions of Mac OS X, Lion has no serial number, no product activation, and no DRM of any kind. In fact, the Mac App Store's licensing policy is even more permissive than past releases of Mac OS X. Here's an excerpt from Lion's license agreement:

    If you obtained a license for the Apple Software from the Mac App Store, then subject to the terms and conditions of this License and as permitted by the Mac App Store Usage Rules set forth in the App Store Terms and Conditions (http://www.apple.com/legal/itunes/ww/) ("Usage Rules"), you are granted a limited, non-transferable, non-exclusive license:

    (i) to download, install, consume and flee for personal, non-commercial use, one (1) copy of the Apple Software directly on each Apple-branded computer running Mac OS X Snow Leopard or Mac OS X Snow Leopard Server ("Mac Computer") that you own or control;

    The references to Snow Leopard are a bit confusing, but hold in intelligence that you requisite Snow Leopard to purchase and download Lion for the first time. I suspect the license agreement will breathe updated once Lion has been out for a while.

    There's furthermore another tantalizing clause in the license, from that same section:

    (iii) to install, consume and flee up to two (2) additional copies or instances of the Apple Software within virtual operating system environments on each Mac Computer you own or control that is already running the Apple Software.

    Putting it utter together, Apple says you're allowed to flee up to three copies of Lion—one real, two inside virtual machines—on every Mac that you own, utter for the low, low cost of $29. Not a contaminated deal.

    The installer itself is deceased simple, foreshadowing the pervasive simplification in Apple's fresh OS. There are no optional installs and no customization. The only response the user provides is agreeing to the obligatory EULA, and the only configurable install parameter is the target disk.

    Enlarge

    But wait a second—how exactly is this going to work? Surely an entirely fresh operating system can't breathe installed on top of the currently running operating system by an application stored on the same volume. Without a plastic disc to boot from, how is it even workable to upgrade a standalone Mac with just one hard drive?

    These questions probably won't occur to an equitable consumer, which is sort of the point, I guess. certain enough, if you just nigh your eyes, launch the installer application, and click your course through the handful of screens it presents, your Mac will reboot into what looks dote the standard Mac OS X installer application from years past. When it's done, your Mac will reboot into Lion. Magic!

    Okay, it's not magic, but it is a bit complicated. The first and most lasting surprise is that the Lion installer will actually repartition the disk, carving out a 650MB slice of the disk for its own use.

    Don't worry, utter existing data on the disk will breathe preserved. (Mac OS X has had the faculty to add partitions to existing disks without destroying any data for many years now.) utter that's required is enough free space to reshuffle the data as needed to originate margin for the fresh partition.

    Here's an sample from my testing. I started with a solitary 250GB hard drive split into two equal partitions: the first named "Lion Ex," currently running Snow Leopard, and the intended target of the Lion install, and the second named "Timex," the Time Machine backup volume for Lion Ex. The output from the diskutil list command appears below.

    /dev/disk1 #: sort cognomen SIZE IDENTIFIER 0: GUID_partition_scheme *250.1 GB disk1 1: EFI 209.7 MB disk1s1 2: Apple_HFS Lion Ex 125.0 GB disk1s2 3: Apple_HFS Timex 124.6 GB disk1s3

    Now here's that same disk after installing Lion, with the fresh partition highlighted:

    /dev/disk1 #: sort cognomen SIZE IDENTIFIER 0: GUID_partition_scheme *250.1 GB disk1 1: EFI 209.7 MB disk1s1 2: Apple_HFS Lion Ex 124.5 GB disk1s2 3: Apple_Boot Recovery HD 654.6 MB disk1s3 4: Apple_HFS Timex 124.6 GB disk1s4

    The fresh partition is actually considered a different type: Apple_Boot. The Recovery HD volume won't breathe automatically mounted upon boot and therefore won't appear in the Finder. It's not even visible in the Disk Utility application, appearing only as a tiny blank space in the partition map for the disk. But as shown above, the command-line diskutil program can descry it. Diskutil can mount it too.

    Doing so reveals the partition as a balanced HFS+ volume. The top plane contains a directory named com.apple.recovery.boot which in revolve contains a few little files related to booting along with an invisible 430MB internally compressed disk image file named BaseSystem.dmg. Mount that disk image and you find a 1.52GB bootable Mac OS X volume containing Safari, most of the contents of the standard /Applications/Utilities folder (Disk Utility, Startup Disk, Terminal, etc.), plus a Mac OS X Lion installer application. In other words, it looks a lot dote a standard Mac OS X installer DVD.

    A subset of the files copied to the recovery partition is furthermore copied to the installation target disk by the installer and blessed as the fresh bootable system. This is what the Lion installer reboots into. The files to install will breathe read from the Lion installer application downloaded earlier from the Mac App Store. After the installation is complete, the temporary boot files are removed, but the Recovery HD partition remains on the disk. Hold down ⌘R during system startup to automatically boot into the Recovery HD partition. (Holding down the option key during startup—not a fresh feature in Lion—will furthermore account for the Recovery HD partition as one of the boot volume choices.)

    Booting from the recovery partition really means mounting and then booting from the BaseSystem.dmg disk image on the recovery partition. Doing so presents a list of the traditional Mac OS X install disc options, including restoring from a Time Machine backup, reinstalling Mac OS X, running Disk Utility, resetting your password, and so on. There's furthermore an option to find back online, which will launch Safari. Including Safari on the recovery partition is a nice touch, since most people's first quit when diagnosing a problem is Google, not the Genius Bar.

    The upshot is that after utter the file compression magic added in Snow Leopard to reduce the footprint of the OS, Lion steals over half a gigabyte of your disk space as allotment of its installation process, and never gives it back. The partition's cognomen makes Apple's intent clear: it's meant as a last-ditch mechanism to diagnose and repair a Mac with a hosed boot volume. (Hosed, that is, in the software sense; existing as it does on the boot disk itself, the recovery partition won't breathe much consume if the disk has hardware problems.)

    Apparently Apple has decided that the faculty to boot a Mac into a known-good (software) condition is well worth sacrificing a little amount of disk space. MacBook Air owners or other Mac users with diminutive solid-state disk drives may disagree, however. In that case, the disk space can breathe reclaimed by some judicious repartitioning with Disk Utility (or the diskutil command-line tool) while booted from another disk. But don't breathe surprised when the fellow at the Genius Bar frowns a puny at your divergence from the Apple Way.

    Reconsidering fundamentals

    The user-visible changes in Lion are legion. You'll breathe hard-pressed to find any allotment of the user interface that remains completely unchanged from Snow Leopard, from the explore and feel utter the course down to basic behaviors dote application and document management. In Lion, Apple has taken a hard explore at the assumptions underlying the last ten years of Mac OS X's development—and has decided that a lot of them requisite to change. find ready.

    Lion's fresh look

    Let's ease into things with a tour of Lion's revised user interface graphics. Though Apple quiet uses the cognomen "Aqua" to advert to Lion's interface, the explore is a far yowl from the lickable, candy-coated appearance that launched the brand. If you can imagine three dials labeled "color," "contrast," and "contour," Apple has been turning them down slowly for years. Lion accelerates that process.

    The shapes occupy started to change, too. The traditional capsule shape of the standard button has given course to a squared-off, Chiclets-style appearance. The tubular shape of the progress bars, a fixture since even before the dawn of Mac OS X, has been replaced with a vaguely puffy stripe of material. Radio buttons, checkboxes, slider thumbs, segmented controls, "tab" controls—nearly everything that used to protrude from the screen now looks as if it was pounded down with a rubber hammer.

    Finder sidebar: grayFinder sidebar: gray

    Even the elements that explore identical, dote the modest gray window title bars, are slightly different from their Snow Leopard counterparts. The fresh explore is not a radical departure—everything hasn't gone jet black and grown fur, for example—but this is the first time that nearly every ingredient of the standard GUI has been changed in a course that's identifiable without a color meter or a magnifying glass.

    For the most part, the fresh explore speaks in a softer voice than its predecessor. The total removal of blue highlights from several controls (e.g., pop-up menus, combo boxes, slider thumbs, and tab controls) makes most interfaces appear slightly less garish. On the other hand, the additional green in the blue highlights that quiet Do exist makes those controls appear more saccharine.

    Apple says that its goal with the Lion user interface was to highlight content by de-emphasizing the surrounding user interface elements. You can descry this most clearly in sidebar and toolbar icons, which are now monochromatic in most of the needful bundled applications. But this has the unfortunate side consequence of making interface elements less distinguishable from each other, especially at the little sizes typical in sidebars. I'm not certain the "increased accent on content" is enough to balance out the loss, especially in applications dote the Finder.

    LionLion Snow LeopardSnow Leopard

    Appearance changes can occupy effects beyond emphasis, fashion, and mood. boost the "traffic light" red, yellow, and green window widgets, for example. As you can descry in the images on the right, they've gotten smaller in Lion. Or rather, the colored portion has gotten smaller; the actual clickable area has lost only one pixel in height and five pixels in total width across utter three widgets.

    But the psychological consequence of the shrunken appearance is something else entirely. Despite the tiny incompatibility in the functional size, I find myself being ever-so-slightly more watchful when targeting these widgets in Lion. It's a puny annoying, especially since it's not transparent to me how the new, smaller size fits into Lion's fresh look. Does such a little reduction in size really serve to better emphasize window content? After all, not a bit of the other controls occupy gotten any smaller.

    Other aspects of the fresh explore occupy clearer intentions. The flatter, more matte explore of most controls, and especially the squared-off shape of the standard button, utter bring to intelligence the explore of Apple's other operating system, iOS. One control in particular takes the iOS connection even further.

    Finally, there's Apple's budding esteem commerce with a particular linen texture. It made its first appearance on the backside of some Dashboard widgets. More recently, it was used as the background pattern for the notifications sheet in iOS 5. In Lion, it's featured even more prominently as the background for the newly restyled login screen, now featuring circular frames for user icons. (Also note the subset of menu bar status icons quiet visible in the top-right corner of the screen.)

    Linen for your login screen Enlarge / Linen for your login screen Scroll bars

    Scroll bars, which Apple likes to summon "scrollers" these days, are among the least-changed interface elements in Mac OS X. While the rest of the Aqua interface was refined—edges sharpened, pinstripes removed, shines flattened—scrollbars stubbornly retained their original Aqua explore for over a decade.

    A scroll bar from Mac OS X DP3, released in 2000A scroll bar from Mac OS X DP3, released in 2000 A scroll bar from Mac OS X 10.6, released in 2009A scroll bar from Mac OS X 10.6, released in 2009

    Scroll bars haven't been entirely static in Mac OS X, however. For many years, iTunes has had its own custom scroll bar look.

    A scroll bar from iTunes 10.2.2, released in 2011A scroll bar from iTunes 10.2.2, released in 2011

    When these fresh scroll bars were first introduced in iTunes 7 in 2006, there was some speculation that this was a tribulation flee for a fresh explore that would soon spread throughout the OS. That didn't happen. But now, five years later, scroll bars are finally changing system-wide in Mac OS X. Here's a scroll bar from Lion:

    A scroll bar from Mac OS X 10.7 LionA scroll bar from Mac OS X 10.7 Lion

    The smeared gradient and fuzzy edges of the iTunes scroll thumb are nowhere to breathe seen. Instead, they occupy a narrow, monochrome, sharp-edged lozenge. Just dote the window widgets, the scroll thumb appears slightly smaller than its Snow Leopard counterpart. (In this case, total scroll bar width and the clickable area are actually the same as in Snow Leopard.)

    The change in appearance might distract you from what's really different: where are the scroll arrows? You know, the puny buttons on either discontinuance of the scroll bar (or grouped together on one end) that you click to skedaddle the scroll thumb a bit at a time? Well, they're gone.

    But wait, there's more. Here's a Finder window.

    The complete contents of Lion's Applications folder…or is it?The complete contents of Lion's Applications folder…or is it?

    Though I can assure you that Lion comes with more than eight applications, you wouldn't know it from looking at this screenshot. Forget about the arrows, where are the scroll bars?

    Placing the cursor into the window and using the scroll wheel on the mouse or two-finger scrolling on a trackpad reveals what you might occupy already guessed based on the shape and appearance of the fresh scroll thumbs. Extremely thin, monochrome scroll thumbs fade in as the scrolling begins, and fade shortly after it ends. These ephemeral scroll thumbs appear on top of the window's content, not in alleys reserved for them on the edges of the window.

    Initiating scrolling (via mouse wheel or trackpad) reveals overlay scroll bars. More applications below!Initiating scrolling (via mouse wheel or trackpad) reveals overlay scroll bars. More applications below! An iOS scroll barAn iOS scroll bar

    These ghostly overlay scroll bars are straight out of iOS. When they were introduced in 2007 on the iPhone's 3.5-inch screen, they made impeccable sense. Dedicating one or more finger-width strips of the screen for always-visible, touch-draggable scroll bars would occupy been a colossal squander of pixels (and anything less than a finger's width of pixels would occupy been too narrow to comfortably use). Overlay scroll bars were essential in iOS, and completely in keeping with its direct manipulation theme. In iOS, you don't maneuver an on-screen control to scroll, you simply grab the whole screen with your finger and skedaddle it.

    Apple isn't (yet) asking us to start poking their fingers at their Mac's screen, but it does now ship every Mac with some benevolent of touch-based input device: internal trackpads on laptops, and external trackpads or touch-sensitive mice on desktops. Lion further cements the dominance of handle by making utter touch-based scrolling travail dote it does on a touchscreen. Touching your finger to a control surface and affecting it downwards will skedaddle the document downwards, revealing more content at top and hiding some of the content that was previously visible on the bottom. This sounds perfectly logical, but it furthermore happens to breathe exactly the opposite how scrolling has traditionally worked with mouse scroll wheels. The consequence is extremely disconcerting, as their fingers unconsciously flick at the scroll-wheel while their eyes descry the document affecting the "wrong" way.

    Scroll direction setting in the Mouse preference pane. Checked means the  fresh Lion scrolling direction is in effect.Scroll direction setting in the Mouse preference pane. Checked means the fresh Lion scrolling direction is in effect.

    Thankfully, there is a preference to restore the dilapidated mapping of finger movement to scroll direction. There's a second setting in the Trackpad preference pane, phrased in the opposite way. Unfortunately, the settings are linked; you can't occupy different values for each benevolent of input device.

    Though the unification of scrolling gestures is logical, it's difficult to find used to after so many years of doing things the other way. The most common scrolling direction is downwards, and the most natural finger movement is curling inwards. These two things align when using a mouse wheel with the "old" scrolling direction setting. dilapidated habits aside, it may breathe that the incompatibility between touching a screen directly and touching a separate device on a horizontal surface in front of the screen is just too considerable to justify a solitary input vocabulary.

    Either way, there's certain to breathe an uncomfortable transition epoch for everyone. For example, the two-finger swipe to the left or birthright used to switch between screens in Launchpad (described later) feels "backwards" when the scroll direction preference is set to the traditional, pre-Lion behavior. Perhaps just seeing a screen covered with a grid of icons unconsciously triggers the "iOS expectations" region of their brains. (And if you set the scroll direction to "feel right" for two-finger swiping in Launchpad, then the four-finger swipe between Spaces feels backwards! Sigh.)

    Scroll bars Do more than just let us scroll. First, their condition tells us whether there's anything more to see. A window with "inactive" (usually shown as dimmed) scroll bars indicates that there is no content beyond what is currently visible in the window. Second, when a document has more content than can appropriate in a window, the scroll bars divulge us their current position within that document. Finally, the size of the scroll thumb itself—or the amount of margin the scroll thumb has to skedaddle within the scroll bar, if you want to explore at it that way—gives some hint about the total size of the content.

    Classic Mac scroll barsClassic Mac scroll bars

    Most computer users aren't conscious of such subtleties, but their combined effects are profound. Long-time Mac users might recollect a time when scroll thumbs were perfectly square regardless of the total size of a window's content. When I assume back to my time using those scroll bars, I don't recall any problems. But just try using these so-called "non-proportional" scroll bars today. The modern computer user's intelligence revolts at the requisite of information, usually treating it instead as deceptive information about the total size of a window's content. ("This window looked dote it had pages and pages of content, but when I dragged the tiny square scroll thumb utter the course from the top to the bottom, it only revealed two fresh lines of text!") Only when this cue is gone Do you realize how much you've been relying on it.

    And hold in intelligence that proportional scroll thumbs are the most subtle of the cues that scroll bars provide. The others are even more widely relied upon. The complete requisite of visible scroll bars leaves a huge information void.

    Let's attach aside the confidential for a moment. In the absence of scroll bars, are there other visual cues that could provide the same information? Well, if truncated content appears at the edge of a window, it's usually a safe stake that there's more content in that direction. The prevalence of whitespace (between icons in the Finder, between lines of text, etc.) can originate such truncation less obvious or even undetectable, but at least it's something. For total content size and position within the document, there's no alternative even that good.

    But panic not, gentle scroller. dote the scroll direction, scroll bar visibility has a dedicated preference (in the universal preference pane):

    Scroll bar settings in the  universal preference paneScroll bar settings in the universal preference pane

    The default setting, "Automatically based on input type," will consume overlay scroll bars as long as there's at least one touch-capable input device attached (though the trackpad on laptops doesn't weigh if any other external pointing devices are connected). If you don't dote this benevolent of second-guessing, just pick one of the other options. The "When scrolling" option means always consume overlay scroll bars, and the "Always" option means always account for scroll bars, using the appearance shown earlier.

    Lion includes fresh APIs for briefly "flashing" the overlay scroll bars (i.e., showing them, then fading them out). Most applications included with Lion briefly account for the scroll bars for windows that occupy just appeared on the screen, occupy just been resized, or occupy just scrolled to a fresh position (e.g., when showing the next match while searching within a document). This helps soften the blow of the missing information previously provided by always-visible scroll bars, but only a little.

    Extra UI in the scroll bar areaExtra UI in the scroll bar area

    Applications with other UI elements whose amend placement relies on the existence of a reserved 16-pixel stripe for the scroll bar outside the content area of the window may breathe forced to array what Apple calls "legacy" scroll bars. (Apple's term for non-overlay scroll bars tells you utter you requisite to know about which course the wind is blowing on this issue.) You can descry an sample of one such UI ingredient in the image on the right. The document scale pop-up menu (currently showing "100%") pushes the horizontal scroll bar to the left to originate margin for itself. Clearly, this will not travail if the scroll bar overlays the content area and is hidden most of the time. Apple suggests that such applications find fresh homes for these interface elements, at which point the AppKit framework in Lion will allow them to array overlay scroll bars.

    Lion's scroll bars are a microcosm of Apple's fresh philosophy for Mac OS X. This is definitely a case of reconsidering a fundamental allotment of the operating system—one that hasn't changed this radically in decades, if ever. It's furthermore nearly a straight port from iOS, which is in keeping with Apple's professed "back to the Mac" mission. But most importantly, it's a concrete sample of Apple's newfound dedication to simplicity.

    In particular, this change reveals the tremendous weight that Apple gives to visual simplicity. A complete requisite of visible scroll bars certainly does originate the equitable Mac OS X screen explore a lot less busy. A requisite of visual clutter has been a hallmark of Apple's hardware and software design for years, and iOS has only accelerated this theme. Also, practically speaking, the sum of utter those 16-pixel-wide stripes reserved for scroll bars on window edges may add up to a nontrivial extend in the number of pixels available for displaying content on a Mac's screen.

    But there is a cost to breathe paid for this simplicity; one person's noise is another person's essential source of information. Visual information, dote the size and position of a scroll thumb, is one of the most efficient ways to communicate with humans. (Compare with, say, numeric readouts showing document dimensions and the current position as a percentage.)

    These sacrifices were an essential allotment of the iPhone's success. The iPad, though larger, is clearly allotment of the same touch-based family of products, and is wisely built on the same foundation. But the Mac is a different kettle of fish—and not just because the screen sizes involved may breathe vastly larger, making the space savings of hidden scroll bars much less important.

    The Mac user interface, with its menus, radio buttons, checkboxes, windows, title bars, and yes, scroll bars, is built on an entirely different interactivity model than iOS. The Mac UI was built for a pixel-accurate circuitous pointing device; iOS was built for direct manipulation with one or more fingers. The visual similarity of on-screen elements and the technical feasibility of porting them from one OS to the other should not blind us to these essential differences.

    It's tantalizing that utter of the scrolling changes in Lion occupy preferences that allow them to breathe reverted to their pre-Lion behaviors. The defaults clearly testify the direction that Apple wants to go, but the settings to invert them—public, with actual GUIs, rather than undocumented plist hacks—suggest caution, or perhaps even some internal strife surrounding these features.

    Such caution is well-founded. Hidden scroll bars in particular occupy trade-offs that change dramatically based on the size of the screen and the input device being used. dote many features in Lion, the scrolling changes are most useful and appropriate on the Macs that are closest to iOS devices in terms of size and input manner (the 11-inch MacBook Air being the best example). But on a Mac Pro with dual 27" 2560x1440-pixel displays attached, Lion's scrolling defaults originate far less sense.

    Window resizing Resize widgetResize widget

    A requisite of traditional scroll bars furthermore means the elimination of the little patch of pixels in the lower-right corner of a window where the perpendicular and horizontal scroll bars meet. Since 1984, this area has been home to the one and only control used to resize a window. Setting the scroll bar appearance preference to "always visible" restores the clickable actual estate, albeit sans the traditional "grip lines."

    Despite the modest appearance, this resize control works as expected; what's unexpected is the cursor change that accompanies the action. The double-arrow cursor has been used in other operating systems for years, mostly to differentiate two-axis resizing (width and height) from single-axis resizing (height only or width only). When there's only one resize control per window, it's obvious that it can breathe used to change both the width and the height. Lion's fresh cursor can breathe of value only one thing…

    Window resizing from  utter edges (composite image)Window resizing from utter edges (composite image)

    That's right, long-suffering switchers, Lion finally allows windows to breathe resized from any edge and from utter four corners, with a special cursor for each of the eight starting points. (When a window is at its size limit, the cursors account for an arrow pointing in a solitary direction—a nice touch.)

    As you can descry from the image above, what Apple hasn't done is add borders to the windows. So where, exactly, Do they "grab" when resizing from a borderless window edge? There's no course around it: some pixels must breathe sacrificed to the gods of Fitts's law.

    A few pixels within the outer edge of the content area of the window (two to three, depending on where you weigh from) are commandeered for window resizing purposes. You can quiet click on these areas, and the click event will correctly propagate to the application that owns the window, but you'll breathe clicking with a resize cursor instead of a balanced arrow cursor.

    Two to three pixels doesn't originate for a very wide target, however, which is why Apple has chosen to appropriate pixels from both sides of the window border. Four to five pixels outside the content area of the window are furthermore clickable for window resizing purposes. Clicks in these areas don't find sent to the window (they're out of the window's bounds) and they don't find sent to whatever happens to breathe behind the active window—you know, the thing that you ostensibly just clicked on. Effectively, Lion windows occupy thin, invisible borders around them used only for resizing. (Unlike Mac OS 8 and 9 windows, which had real, visible borders, Lion windows can't breathe dragged by their borders.)

    When overlay scroll bars are in use, the complete 16x16 pixel home of the traditional resize widget in the lower-right corner is clickable, making this quiet the easiest target for window resizing, whether it's visible or not.

    Unzoom widgetUnzoom widget Zoom widgetZoom widget

    Lion has a few more surprises on window edges, one of which is window size-related. Windows belonging to applications that support Lion's fresh full-screen mode may account for an embossed double arrow icon on the far-right side of their title bars. Clicking it will understanding the window to fill the entire screen. Other windows, the Dock, and even the menu bar are hidden in this mode. The window's title bar furthermore disappears, making it unclear how to exit this mode. But just stab the cursor at the top of the screen and the menu bar slides back down into view, containing utter the expected menus plus a reversed version of the double arrow symbol. Click the inward-facing arrows to boost the current window out of full-screen mode.

    Animation

    Mac OS X has always used animation in its user interface, starting with the genie consequence over a decade ago, and really ramping up with the introduction of the Core Animation framework three years ago. Lion continues this trend. In nearly utter fresh or changed applications in Lion, if something conceivable can breathe animated, it is. The Finder is a advantageous example. Even features whose functionality hasn't actually changed in Lion, such as dragging multiple items from one window to another, are given a fresh coating of animation and fades.

    At its best, animation explicitly communicates information that was either absent or only implied before. For example, the genie animation tells the user where a window goes when it's minimized. In other cases, such as the water ripple consequence in Dashboard, animation can add a bit of fun to an interface.

    But danger lurks. A newly discovered animation might delight the user the first time it's shown, but the 350th time might not look quite so magical. This is especially suitable if the animation adds a retard to the task, and if that assignment is done frequently as allotment of a time-sensitive overall task. The Dashboard water ripple is acceptable because adding a fresh widget to the screen is an infrequent task. But if the screen rippled every solitary time a fresh window appeared anywhere in the OS, users would revolt.

    Well, guess what happens every time a fresh window appears on the screen in Lion? No, it's nothing as garish as a water ripple, but there is an animation. Each window starts as a tiny dot centered on the window's eventual position on the screen, then quickly animates to its complete size.

    This animation conveys no fresh information. It does not divulge the user where a window came from, since the animation starts at the final position of the window. Whether or not the animation actually delays the opening of the window, it certainly feels dote it does, which is even more important. This sort of animation can originate Lion feel slower than Snow Leopard. And when an animation dote this stutters or skips a few frames due to hefty disk i/o or CPU usage, it makes your whole Mac feel slower, dote you're playing a 3D game with an inadequate video card. And for what? For what someone at Apple hopes will breathe a lasting sentiment of delight?

    Perhaps it could breathe argued that the animation catches the eye more than a window that appears instantly (though that probably depends on the size of the window and what's behind it on the screen). For "unexpected" windows dote oversight dialog boxes, that could breathe a benefit. But for "expected" windows (i.e., those that appear in response to deliberate user input), the powerful, primordial haul of these affecting images is an unwelcome distraction, not a benefit.

    It's conceivable that this animation could delight some users, but I occupy a hard time believing that the enjoyment will last much past the first week. (Interestingly, this animation does not play in invert when a window is closed. This, perversely, makes window closing feel faster than window opening in Lion.)

    Unlike the scrolling behaviors discussed earlier, there are no user-visible preferences for these fresh animations, which makes it utter the more needful for Apple to strike a advantageous balance. In my estimation, Lion crosses the line in a few places; the fresh window animation is the most egregious example. I explore forward to discovering a course to disable it. [Update: here it is: defaults write NSGlobalDomain NSAutomaticWindowAnimationsEnabled -bool NO]

    Here's to the crazy ones

    Bruce Tognazzini, founder of the Apple Human Interface Group and 14-year Apple veteran (1978-1992), is best known as the man behind the publication of the Apple Human Interface Guidelines. In 1992, he published a reserve of his own: Tog on Interface. Most of the examples in the reserve were taken from his travail at Apple. Here's an excerpt from pages 156-157:

    Natural objects occupy different perceivable characteristics, among which people can easily discriminate. boost the bristlecone pine. The oldest living thing on earth, it has been formed and shaped by the wind and scarred by thousands of years of existence. The youngest school kids explore at it and know there must breathe a lot of wind around there. They know the pine may breathe even older than their father. They furthermore know, to a certainty, that it is a tree.

    Hypercard "Home" iconsHypercard "Home" icons

    Kristee Kreitman Rosendahl, responsible for not only the graphic design of HyperCard, but furthermore much of its spirit, created a collection of Home icons that shipped with the product.

    No one has ever shown confusion at seeing various puny houses on various cards. Never once has someone turned around and said, "Gee, this puny house has three windows and seems to breathe a Cape Cod. Will that boost me to a different Home card than that two-story bunk house back in the other section?" People are designed to maneuver multiplexed meanings gracefully, without conscious thought.

    In System 7, they multiplexed the sense of system extensions, by developing a characteristic "generic" extension look, to which developers can add their own unique explore for their specific product. As the "bandwidth" of the interface increases, these kinds of multiplexings will become more and more practical.

    System 7 extension iconsSystem 7 extension icons

    This is Tog, godfather of the old-school Apple Human Interface Guidelines, stating emphatically that interface elements Do not occupy to explore exactly the same in order for their duty to breathe discerned. In fact, in the final sentence, Tog predicts that increased computing power will lead to more diverse representations. The increased "bandwidth" of user interfaces that Tog wrote about almost 20 years ago has now gain to pass, and then some.

    Examples of "multiplexed meanings" in Mac OS X are not hard to find. explore at the Dock, which has changed appearance several times during the history of Mac OS X while quiet remaining immediately identifiable. And, as discussed earlier, nearly every standard GUI control has changed its appearance in Lion. As Tog notes, people are excellent at discarding unimportant details and focusing on the most salient aspects of an item's appearance.

    Now, keeping utter this in mind, I invite you to ogle upon this screenshot of the version of iCal that ships with Lion.

    A stitch in time saves…something, presumably

    Enlarge / A stitch in time saves…something, presumably

    When this change was first revealed in the second developer preview of Lion, there was much gnashing of teeth. But inquire yourself, is the duty of every control in the toolbar clear? Or rather, is it any less transparent than it would breathe if iCal used the standard Mac OS X toolbar appearance?

    The immediate, visceral negative reaction to the wealthy Corinthian leather appearance had puny to Do with usability. What it came down to—what first impressions dote these always look to gain down to—is whether or not you assume it's ugly. People will boost "really cool-looking but slightly harder to use" over "usable but ugly" any day.

    But there's something much more needful than the change in appearance going on here. Lion's iCal doesn't explore different in an whimsical way; it's been changed with purpose. After the initial stitched-leather shock wore off, Apple watchers everywhere leapt on the fresh iCal's deeper sin: its skeuomorphic design. From Wikipedia (emphasis added):

    A skeuomorph is a derivative demur that retains ornamental design cues to a structure that was necessary in the original. Skeuomorphs may breathe deliberately employed to originate the fresh explore comfortably dilapidated and familiar, such as copper cladding on zinc pennies or computer printed postage with circular town cognomen and cancellation lines. An alternative definition is "an ingredient of design or structure that serves puny or no purpose in the artifact fashioned from the fresh material but was essential to the demur made from the original material."

    Apple has been down this road before, most notably with the QuickTime 4.0 player application which included bright ideas dote a "dial" control for adjusting the volume. Dials travail considerable in the real, physical world, and are certainly confidential to most people. But a dial control in the context of a 2D mouse-driven GUI is incongruous and ungainly at best, and completely incomprehensible at worst.

    The brushed metal appearance of the QuickTime player would later inspire an officially supported Mac OS X window appearance starting in version 10.2, only to breathe dropped completely five years later in 10.5's grandiose interface unification. Now, three years after that, the pendulum is swinging in the other direction again—and hard.

    In the case of iCal, Apple has aped the appearance of an analogous physical demur (a tear-off paper calendar) but retained the conduct of standard Mac OS X controls. This avoids the problems of the QuickTime 4.0 player's dial control, but it's far from a antiseptic win.

    The concern is, the fresh iCal looks so much dote a confidential physical demur that it's effortless to start expecting it to behave dote one as well. For example, iCal tries very hard to sell the tear-off paper calendar illusion, with the stitched binding, the tiny remains of already-removed sheets, and even a page curl animation when advancing through the months. But can you grab the corner of a page with your mouse and split it off? Nope, you occupy to consume the arrow buttons or a keyboard command, just dote in the previous version of iCal. Can you scribble in the margins? Can you cross off days with a pen? Can you riffle through the pages? No, no, and no.

    At the same time, iCal is quiet constrained by some of the limitations of its physical counterpart. A paper calendar must pick a solitary course to rupture up the days in the year. Usually, each page contains a month, but there's no understanding for a virtual calendar to breathe limited in the same way. When dealing with events that span months, it's much more convenient to view time as a continuous stream of weeks or days. This is especially suitable on large desktop monitors, where zooming the iCal window to complete screen doesn't account for any more days but just makes the days in the current month larger.

    The fresh version of Address reserve in Lion is an even more egregious example.

    These graphics are writing checks this interface can't cash Enlarge / These graphics are writing checks this interface can't cash

    Address reserve goes so far in the direction of imitating a physical analog that it starts to impair the identification of standard controls. The window widgets, for example, are so integrated into the design that they're effortless to overlook. And as in iCal, the Amazing detail of the appearance implies functionality that doesn't exist. Pages can't breathe turned by dragging, and even if they could, the number of pages on either side of the spine never changes. The window can't breathe closed dote a book, either. That red bookmark can't breathe pulled up or down or removed. (Clicking it actually turns the page backwards to betray the list of groups. Did you guess that?) The three-pane view (groups → people → detail) is gone, presumably because a reserve can't account for three pages at once. Within each paper "page" sits, essentially, an excerpt from the user interface of the previous version of Address Book. It's a mixed metaphor that sends mixed signals.

    These newly redesigned Mac OS X applications are clearly inspired by their iOS counterparts, which suffer similar graphical flourishes and skeuomorphic design elements. (Address reserve in particular is a deceased ringer for the Contacts app on the iPad.) In iOS, the inability to revolve pages with the flick of a finger or yank out that tantalizing red bookmark is even more frustrating. In both environments, when the behaviors seemingly promised by the graphical design aren't delivered, utter this artwork that was so clearly labored over fades into the background. The application trains us to ignore it. What was once, at best, a momentary amusement is reduced to visual noise.

    In 2011, we're far past the point where computer interfaces requisite to reference their forebearers in the physical world in order to breathe understandable (though it's workable Apple thinks the familiarity of such designs is quiet an effective course to reduce intimidation, especially for novice users). At the same time, hardware and software occupy advanced to the point where there's now ample "bandwidth" (to consume Tog's term) to support visual and functional nuances beyond the bare necessities.

    Interface designers are faced with the challenge of how best to consume the glut of resources now at their disposal. As Lion's iCal and Address reserve applications demonstrate, an alternate description of this situation might breathe "enough rope to hang yourself."

    Window management

    Over the years, Apple has added several features that could loosely breathe defined as "window management aids." The first, and arguably most successful, was Exposé, introduced in Panther back in 2003. Two years later, Tiger shipped with Dashboard, which provided a dedicated screen for little "widget" windows, keeping them off the main screen. In 2007, Leopard brought official support for virtual desktops to Mac OS X under the cognomen Spaces.

    Each of these features came with its own set of configurable keyboard shortcuts, tart screen corners, and (eventually) multi-touch gestures. While each was understandable and useful in isolation, it was up to each user to device out how best to incorporate them into a workflow. In Lion, Apple has taken a stab at consolidation under the umbrella cognomen of Mission Control. Each individual feature quiet exists, albeit in slightly more limited forms, but activating one thing now provides access to them all.

    Using any one of the supported Mission Control activation methods—a keyboard shortcut, a tart screen corner, or a four-finger upwards swipe—causes the current desktop picture to recede slightly into the center of the screen, revealing behind it their dilapidated friend the linen pattern. Overlaid on this are groups of windows, badged by the icons of the applications to which they belong. Along the top of the screen sit utter open Spaces. (In Lion, each full-screen window creates a fresh Space, so those windows appear at the top rather than grouped with the other windows from the same application.) Dashboard is furthermore (optionally) given its own Space.

    Mission Control: Exposé + Spaces + Dashboard Enlarge / Mission Control: Exposé + Spaces + Dashboard

    A surprising number of things can breathe done from this screen. As with Exposé, clicking on any window will bring it to the front. Windows can furthermore breathe dragged into any of the available Spaces (excluding Dashboard and those that hold a solitary full-screen window). affecting the cursor (or dragging a window) to the upper-right corner of the screen causes a panel with a "+" character to appear; clicking this creates a fresh space. Holding down the option key makes Dashboard-style "close" widgets appear on any non-fullscreen-window Spaces (except the original Desktop Space, which can never breathe closed).

    The biggest limitation of this fresh arrangement is that Spaces are now confined to a one-dimensional line of virtual desktops. Four-finger swiping between spaces feels great, but there's no wrap-around when you hit the end.

    As large a step down as this is from the much more flexible grid arrangement of Spaces in earlier versions of Mac OS X, the fresh limitations are probably a advantageous idea. The fresh conduct of full-screen windows and the surprisingly natural-feeling four-finger swipes used to switch between them and enter Mission Control means that many more Mac users will likely find themselves using these fresh features than ever used the combination of Exposé and Spaces in earlier versions of the OS. A simple line of spaces with no wrap-around provides a safe, understandable environment for utter these fresh Spaces users.

    For the experts, well, consolidation always has its price. In this case, as in many others, Apple has decided that the advantageous of the many outweighs the advantageous of the few.

    Application management

    For utter its warts, the radical simplification of application management brought to Mac OS X by the Dock really has benefitted the platform. As I wrote in my ten year Mac OS X retrospective, "For every user who continues to breathe frustrated by the Dock's limitations, there are thousands of others who are buoyed in their computing efforts by its reassuring simplicity and undemanding design."

    But the Dock falls short, especially for novice users, as an application launcher. Or rather, it falls short if the application to breathe launched isn't actually in the Dock. Most novice users I know want to occupy every application they are likely to consume available in the Dock at utter times. As these users gain experience, the Dock can become a very crowded place. But why are these increasingly Mac-savvy users stuffing their Docks to the gills rather than limiting its contents to just the applications they consume most frequently?

    The retort lies in how applications not in the Dock are located and launched. Choices involve the Finder, Spotlight, or (I suppose) a Terminal window. affecting from an always-visible line of colorful icons that's front and center on the screen to any one of those alternatives represents a huge extend in conceptual and mechanical complexity.

    If you don't understand how typing the cognomen of an application into a search box can breathe so much more difficult than clicking an icon in the Dock, I hint that you occupy not spent enough time with novice users. Such users often don't even know the cognomen of the application they want—or if they do, they don't know how to spell it. That's before considering the frequent disorientation caused by the rapid-fire search results refinement animation in the Spotlight menu, or the existence of multiple files whose contents or names hold the string being searched for. And this utter assumes novices know (or remember) what Spotlight is and how to activate it in the first place.

    The jump in complexity from the Dock to the Finder, I think, needs less explanation. As a universal rule, novice users just don't understand the file system. They don't understand the hierarchy of machines, devices, and volumes; they don't grasp the concept of the current working directory; they don't know how to identify a file or folder's position within the hierarchy. panic of the file system practically defines novice users; it is usually the last and biggest hurdle in the journey from timorous experimentation to basic technical competence.

    To attach it another way, your dad can't find it if it's not in the Dock. (Well, my dad can't, anyway. Sorry to utter the Mac-savvy dads out there; I am one, after all.)

    In Lion, Apple aims to fill that gap with an application launching interface that's meant to breathe as effortless to consume as the Dock while providing access to every application on the system. It's called Launchpad, and you'll breathe forgiven for thinking that it looks dote yet another interface ingredient shamelessly ported from iOS.

    Launchpad: iOS’s SpringBoard on your Mac Enlarge / Launchpad: iOS’s SpringBoard on your Mac

    Launchpad can breathe activated with a Dock icon (which, importantly, is in the Lion Dock by default), a multitouch signal (a significantly ungainly pinch with the thumb and three fingers), or by dragging the mouse cursor to a designated corner of the screen. The grid of application icons that appears doesn't just explore dote iOS's SpringBoard, it furthermore behaves dote it, birthright down to the "folders" created by dragging icons on top of each other.

    Holding down the option key makes utter the icons sprout nigh widgets as they start to wiggle. Swiping birthright and left on the touchpad or with a click and drag of the mouse will skedaddle from screen to screen, accompanied by a confidential iOS-like dotted page indicator.

    Launchpad “folders” Enlarge / Launchpad “folders”

    Launchpad will find applications in the standard /Applications folder as well as ~/Applications (i.e., a folder named "Applications" in your home directory), and any subfolders within them. Applications in the ~/Downloads folder or on the desktop are not detected, which may actually breathe a problem for Mac users who occupy not yet figured out how to execute drag-and-drop application installations—yet another area where the Mac App Store will back originate things simpler.

    Mac App Store download progressMac App Store download progress

    Speaking of which, when purchasing an application in the version of the Mac App Store that ships with Lion, the application icon leaps out of the Mac App Store window and lands in the next available position in the Launchpad grid, with an iOS-like progress bar overlaid on the fresh application's icon. If the Launchpad icon is in the Dock, it displays a similar progress bar and the icon bounces once when the download finishes.

    Both serve as examples of animation that conveys useful information. "Here's where the application you just purchased has 'landed' on your Mac," the animation says. "To find it again, click the icon that just bounced in your Dock."

    Given the wealth of excellent third-party application launchers available for the Mac, I'm not certain there's any understanding for an expert user to consume Launchpad instead of their current favorite alternative. But unlike, say, the Dock, Launchpad is easily ignored. revolve off the gesture, deactivate the tart corner, and remove the icon from the Dock and you'll never occupy to descry it.

    For everyone else, however, Launchpad will provide a huge improvement in usability. Even expert users should breathe excited about its arrival because it should originate telephone or e-mail-based family technical support a bit easier.

    Document model

    Lion introduces what Apple calls, with characteristic conviction, a "modernized" document model. I'm inclined to correspond with this word choice. dote so many other aspects of Lion, document management is attempting to shed its legacy baggage—and there's plenty to shed. The conventions governing the interaction between users, applications, and documents occupy not changed much since the personal computer became accepted in the early 1980s.

    Apple first attempted a minor revolution in this area with OpenDoc in the 1990s. Instead of launching an application in order to create a document, OpenDoc promised a world where the user would open a document and then travail on it using an interchangeable set of components created by multiple vendors. In other words, OpenDoc was document-centric rather than application-centric.

    The changes in OpenDoc promised to radically shift the balance of power in the application software market. But powerful software companies dote Microsoft and Adobe were not particularly motivated to rupture their popular, full-featured applications into smaller components that customers could amalgamate and match with components from other vendors. At the time OpenDoc was released, Apple was nearing the nadir of its popularity and influence in the industry. Predictably, OpenDoc died on the vine.

    Fast-forward to today, where a much more powerful and confident Apple takes another crack at the same area. The most pressing problem, today's Apple has decided, is not the interaction between application code and document data, but rather the interaction between the user and the computer.

    Despite decades of public exposure to personal computers, human expectations and habits occupy stubbornly refused to align with the traditional model of creating, opening, and saving documents. The tales of woe occupy become clichés:

  • The student who writes for an hour without saving and loses everything when the application crashes.
  • The businessman who accidentally saves over the "good" version of a document, then takes it upon himself to independently reinvent version control—poorly—by compulsively saving each fresh revision of every document under slightly different names.
  • The Mac power user who reflexively selects the "Don't Save" button for one document after another when quitting an application with many open windows, only to accidentally lose the one document that actually had needful changes.
  • The father who swears he saved the needful document, but can't, for the life of him, recollect where it is or what he called it.
  • At this point, they can no longer summon this a problem of education. We've tried education for years upon years; children occupy been born and grown to adulthood in the PC era. And yet even the geekiest among us occupy lost data, time, or both due to a "stupid" mistake related to creating, opening, and saving documents.

    And so Apple's decree in Lion is as it was on the original Macintosh in 1984, and as it is on iOS today: the machine must serve the human, not the other course around. To that end, Apple has added APIs in Lion that, when used properly, enable the following experience.

  • The user does not occupy to recollect to redeem documents. utter travail is automatically saved.
  • Closing a document or quitting an application does not require the user to originate decisions about unsaved changes.
  • The user does not occupy to recollect to redeem document changes before causing the document's file to breathe read by another application (e.g., attaching an open document with unsaved changes to an e-mail).
  • Quitting an application, logging out, or restarting the computer does not breathe of value that utter open documents and windows occupy to breathe manually re-opened next time.
  • Earlier versions of Mac OS X supported a configuration of automatic saving. If you had an open TextEdit document with unsaved changes, TextEdit would (eventually) redeem a backup copy of the file with the text " (Autosaved)" appended to the file name. If the application crashed or the Mac lost power, you could retrieve (some of) your unsaved changes by finding the autosaved file and opening it.

    Lion introduces a variant of this practice: autosave in place. Rather than creating a fresh file alongside the original, Lion continuously saves changes directly to the open document. It does this when there are large document changes, during idle times, or on demand in response to requests from other applications for access to the document's data.

    For utter of this to work, applications must breathe updated to consume the fresh APIs. In particular, a fresh File Coordination framework must breathe used in order for an application to notify another that it wants to access a document that's currently open. The application that has the document open will then trigger an autosave to disk before allowing the requesting application to reference the document's data. Attaching a document to an e-mail or using Quick explore in the Finder are two examples of when this might happen.

    At this point, a puny bit of "geek panic" might breathe setting in. For those of us who understand the pre-Lion document model and occupy been using it for decades, the concept that they are no longer in control of when changes to open documents are saved to disk seems insane! What if I accidentally delete a huge swath of text from a document and then Lion decides to autosave immediately afterwards?

    Not every change is meant to breathe saved, after all. The practice of speculatively making radical changes to a document with the comfort of knowing that not a bit of those changes are permanent until they hit ⌘S is something experienced Mac users boost for granted and may breathe loath to give up.

    The artist formerly known as “Save”The artist formerly known as “Save”

    I confess, I omitted one particular from the list of changes enabled by Lion's modern document model. Here it is:

  • The user does not occupy to manually manage multiple copies of document files in order to retrieve dilapidated versions.
  • If you quiet don't find it, check out the particular in the File menu formerly known as "Save." It now reads "Save a Version" instead. Every time a Lion-savvy application autosaves a document, it stores a copy of the previous version before it overwrites the file with the fresh data. A pop-up menu in the title bar of each document window provides access to previous versions.

    A menu in the title bar provides access to previous versions of a fileA menu in the title bar provides access to previous versions of a file

    Select the "Browse utter Versions…" menu particular to enter a Time Machine-like space-themed screen showing utter previous versions of the file. Using this interface, the document can breathe reverted to any earlier version, or snippets of data from earlier versions may breathe copied and pasted into the current version. Though the star territory background and surrounding timeline interface are provided automatically, the document windows themselves are actual windows within the application. They can breathe scrolled and manipulated in any course allowed by the application, though the contents of previous versions may not breathe modified.

    Document version browser…in spaaaaace! Enlarge / Document version browser…in spaaaaace!

    The standard Cocoa document framework will manage many of the details for application developers, including automatically purging very dilapidated versions of files. The document versioning interface shown above is furthermore integrated with Time Machine, showing both locally stored file versions and older versions that only exist on the Time Machine backup volume. Going forwards or backwards in the document timeline is accompanied by a tidy star-field "warp" animation.

    Restoring the document to an earlier condition actually just pushes a duplicate of that condition to the front of the stack of utter changes. In other words, restoring a document to its condition as of an hour ago does not discard utter the changes that happened during that hour.

    Returning to the title bar pop-up menu, the "Revert to last Saved Version" menu particular returns the document to its last explicitly saved condition (i.e., what it looked dote the last time the user typed ⌘S or selected the "Save a Version" menu item). "Duplicate" will create a fresh document containing the same data as the current document. Finally, the "Lock" particular will forestall any further changes to the document until it is explicitly unlocked by the user. Documents will furthermore automatically breathe locked if they're not modified for a puny while. The auto-lock time is configurable in the "Options…" screen of the Time Machine preference pane (of utter places), with values from one day to one year. The default is two weeks.

    The auto-lock  retard setting, cleverly hidden in the Time Machine preference paneThe auto-lock retard setting, cleverly hidden in the Time Machine preference pane

    There is no graphical interface to previous versions of documents outside of an application. Previous versions can't breathe viewed or restored from within the Finder, for example. Forcing utter version manipulation to breathe within the application is limiting, but it furthermore neatly solves the problem of how to present document contents with complete fidelity—beyond what Quick explore offers—when looking at past revisions.

    One unexpected implication of autosave is that it makes quitting applications much less painful. If you've ever had to quickly log out or shut down a Mac that has been up and working hard for weeks or months, you know how abominable it is to occupy to wade through umpteen dialog boxes, each demanding a decision about unsaved changes before allowing you to continue.

    These are not effortless questions, especially for files that may occupy been open for a long time. attach aside deciding whether the changes are worth saving; can you even recollect what the unsaved changes are? Were they intentional, or did you accidentally skinny on the keyboard and delete a selected particular some time last week? Now multiply this spot by the number of open documents with unsaved changes—and imagine you're in a hurry. It's not a pleasant experience.

    Autosave eliminates these hassles. Quitting an application that supports autosave happens instantly, with no additional user input required—always.

    Of course, by quitting an application (or quitting utter applications by logging out or restarting) you're furthermore losing utter of your accumulated state: utter your open documents, the size and position of their windows, scroll positions, selection state. Losing condition can prove even more painful than playing "20 questions" with a swarm of "unsaved changes" dialog boxes. Assuming you can recollect what documents you had open, can you find them again?

    Lion offers fresh APIs to address this problem as well. A suite of fresh condition encoding/decoding hooks allow Lion applications to redeem and restore any and utter aspects of document state. Upon relaunch, an application is expected to restore utter the documents open when it was last quit, with utter their condition preserved.

    So, how's that "geek panic" now? quiet there, huh? Well, let me try to reassure you. As a committed user of a considerable Mac text editor that, years ago, implemented its own version of almost utter the document management features described so far, I can divulge you that you find used to it very quickly. Spoiled by it, in fact. Ruined by it, some would say. Yes, it's a very different model from the one we're utter used to. But it's furthermore a better model—not just for novices, but for geeks too.

    Think about it: never lose data because you forgot to save. Quit applications with impunity. Retrieve dilapidated versions of documents at any time, in whole or in part. Build up a nice arrangement of open documents and windows, knowing that your hard travail will not breathe trashed the next time you quit the application or requisite to restart for an OS security update.

    The final piece of the perplex is not strictly document-related, but it puts the bow on the package. When logging out or restarting, Lion presents an option (selected by default) to restore utter open applications when you next log in. And relaunching a Lion-savvy application, of course, causes it to restore its open documents.

    Putting it utter together, this means that you can log out or shut down your Mac without being asked any questions by needy applications and without losing any of your data or window state. When you next log in, the screen should explore exactly the same as it did just before you logged out. (In fact, Lion appears to "cheat" and briefly presents a static image of your earlier screen while it works on relaunching your apps and restoring your open documents. Sneaky, but an effective course to originate condition restoration feel faster than it really is.)

    Process model

    If you were flipping out over the document changes described in the previous section, buckle up, because the discomfort plane is about to surge yet again.

    The little indicator lights shown beneath running applications in the Dock are now optional in Lion.

    Three of these applications are runningThree of these applications are running

    In pre-release builds of Lion, utter applications in the Dock looked exactly the same, running or otherwise. At the last minute, it seems Apple chickened out and enabled the indicator lights by default.

    Dock indicator lights preferenceDock indicator lights preference

    Apple's message with this feature is a simple one, but furthermore one that the nerdly intelligence rebels against: "It doesn't matter if an application is running or not. You shouldn't care. quit thinking about it." Geek panic!

    Remain calm. Let's start with the APIs. Sudden Termination, a feature that was introduced in Snow Leopard, allows applications to testify to the system that it's safe to execute them "impolitely" (i.e., by sending them SIGKILL, causing them to terminate immediately, with no random for potentially time-consuming clean-up operations to execute). Applications are expected to set this bit when they're certain they're not in the middle of doing something, occupy no open files, no unflushed buffers, and so on.

    This feature enables Snow Leopard to log out, shut down, and restart more quickly than earlier versions of Mac OS X. When it can, the OS simply kills processes instead of politely asking them to exit. (When Snow Leopard was released, Apple made certain its own applications and daemon processes supported Sudden Termination, even if third-party applications didn't.)

    Lion includes a fresh feature called Automatic Termination. Whereas Sudden Termination lets an application divulge the system when it's okay to terminate it with extreme prejudice, Automatic Termination lets an application divulge the system that it's okay to politely inquire the program to exit.

    But wait, isn't it always okay for the OS to politely inquire an application to exit? Isn't that what's always happened in Mac OS X on logout, shutdown, or restart? Yes, but what makes Automatic Termination different is when and why this might happen. In Lion, the OS may terminate applications that are not in consume in order to reclaim resources—primarily memory, but furthermore things dote file descriptors, CPU cycles, and processes.

    You read that right. Lion will quit your running applications behind your back if it decides it needs the resources, and if you don't appear to breathe using them. The heuristic for determining whether an application is "in use" is very conservative: it must not breathe the active application, it must occupy no visible, non-minimized windows—and, of course, it must explicitly support Automatic Termination.

    Automatic Termination works hand-in-hand with autosave. Any application that supports Automatic Termination should furthermore support autosave and document restore. Since only applications with no visible windows are eligible for Automatic Termination, and since by default the Dock does not testify whether or not an application is running, the user might not even notice when an application is automatically terminated by the system. No dialog boxes will inquire about unsaved changes, and when the user clicks on the application in the Dock to reactivate it, it should relaunch and appear exactly as it did before it was terminated.

    This is effectively a deprecation of the Quit command. It also, perhaps coincidentally, solves the age-old problem of former Windows users expecting applications to terminate when they no longer occupy any open windows. When Automatic Termination is enabled in an application, that's exactly what will happen—if and when the system needs to reclaim some resources, that is.

    As if utter of this isn't enough, Lion features one final application management twist. When an application is terminated in Lion, utter the customary things appear to happen. If the running application indicator is enabled, the little dot will fade from beneath the application's Dock icon. Assuming it's not a permanent resident, the application icon will fade from the Dock. The application will no longer appear in the command-tab application switcher, or in Mission Control. You might therefore conclude that this application's process has terminated.

    A quick trip to the Activity Monitor application or the "ps" command-line utility may discourage you of that notion. Lion reserves the birthright to hold an application's process around just in case the user decides to relaunch it. Upon relaunch, the application appears to start up instantly—because it was never actually terminated, but was simply removed from utter parts of the GUI normally occupied by running applications.

    That's right, gentle readers. In Lion, an ostensibly "running" application may occupy no associated process (because the operating system automatically terminated it in order to reclaim resources) and an application may occupy a process even when it doesn't appear to breathe running. Applications without processes. Processes without applications. Did Lion just blow your mind?

    The pitch

    The application and document model changes in Lion are a radical rupture with the past—the past of the desktop, that is. Everything described above has existed since day one on Apple's mobile platform. Indeed, iOS is the most compelling dispute in favor of the changes in Lion. For every objection offered by a long-time personal computer aficionado, there are millions of iOS users countering the dispute every day with their fingers and their wallets.

    These changes in Lion are meant to reduce the number of things the user has to dependence about. And while you may assume you really Do requisite to dependence about when your documents are saved to disk or when the recollection occupied by an application is returned to the system, you may breathe surprised by how puny you assume about these things once you become accustomed to the computer managing them for you. If you're an iOS user, assume about how often you've wanted a "Save" button in an app on your iPhone or iPad, for example.

    So that's the pitch: Lion will bring the worry-free usability of iOS application and document management to the Mac. For the vast majority of Mac users, I assume it will breathe an effortless sale.

    The reality

    There's a common thread running through utter of the application and document model features described above: they're utter opt-in, and developers must add code to their applications to support them. Apple has some faculty to hasten the transition to Lion-savvy applications through evangelism, positive reinforcement (the carrot), and the increasing popularity of the Mac App Store (the stick). But no matter what Apple does, the idyllic image of an iOS-like experience on your Mac will boost a long time to materialize.

    In the meantime, it's effortless to envision a frustrating hodgepodge of dilapidated and fresh Mac applications running on Lion, making users second-guess their hard-won computing instincts at every turn. What I assume will actually happen is that the top-tier Mac developers will quickly add support for some or utter of these fresh features and users will start to explore down on applications that quiet behave the "old way." I'm certain that's how Apple hopes things revolve out, too.

    Internals

    The previous release of Mac OS X focused on internal changes. My review did the same, covering compiler features, programming language extensions, fresh libraries, and other details that were mostly invisible to end-users.

    Lion is most definitely not an internals-focused release, but it's furthermore large enough that it has its partake of needful changes to the core OS accompanying its more obvious user-visible changes. If this is your first time reading an Ars Technica review of Mac OS X and you've made it this far, breathe warned: this section will breathe even more esoteric than the ones you've already read. If you just want to descry more screenshots of fresh or changed applications, feel free to skip ahead to the next section. They nerds won't assume any less of you.

    Security

    Apple's approach to security has always been a bit unorthodox. Microsoft has spent the last several years making security a top priority for Windows, and has done so in a very public way. Today, Windows 7 is considered vastly more secure than its widely exploited ancestor, Windows XP. And despite the fact that Microsoft now distributes its own virus/malware protection software, a burgeoning market quiet exists for third-party antivirus software.

    Meanwhile, on the Mac, Apple has only very recently added some basic malware protection to Mac OS X, and it did so quietly. Updates occupy been similarly quiet, giving the impression that Apple will only talk about viruses and malware if asked a direct question about a specific, actual piece of malicious software.

    This approach is typical of Apple: don't roar anything until you occupy something meaningful to say. But it can breathe maddening to security experts and journalists alike. As for end-users, well, until there is a security problem that affects more than a tiny minority of Mac users, it's hard to find an sample of how Apple's policies and practices occupy failed to protect Mac users at least as well as Microsoft protects Windows users.

    Sandboxing

    Just because Apple is quiet, that doesn't breathe of value it hasn't been taking actual steps to better security on the Mac. In Leopard, Apple added a basic configuration of sandboxing to the kernel. Many of the daemon processes that originate Mac OS X travail are running within sandboxes in Snow Leopard. Again, this was done with puny fanfare.

    Running an application inside a sandbox is meant to minimize the damage that could breathe caused if that application is compromised by a piece of malware. A sandboxed application voluntarily surrenders the faculty to Do many things that a balanced process flee by the same user could do. For example, a balanced application flee by a user has the faculty to delete every solitary file owned by that user. Obviously, a well-behaved application will not Do this. But if an application becomes compromised, it may breathe coerced into doing something destructive.

    In Lion, the sandbox security model has been greatly enhanced, and Apple is finally promoting it for consume by third-party applications. A sandboxed application must now involve a list of "entitlements" describing exactly what resources it needs in order to Do its job. Lion supports about 30 different entitlements which gain from basic things dote the faculty to create a network connection or to listen for incoming network connections (two separate entitlements) to sophisticated tasks dote capturing video or quiet images from a built-in camera.

    It might look dote any nontrivial document-based Mac application will, at the very least, requisite to declare an entitlement that will allow it to both read from and write to any directory owned by the current user. After all, how else would the user open and redeem documents? And if that's the case, wouldn't that entirely rout the purpose of sandboxing?

    Apple has chosen to decipher this problem by providing heightened permissions to a particular class of actions: those explicitly initiated by the user. Lion includes a trusted daemon process called Powerbox (pboxd) whose job is to present and control open/save dialog boxes on behalf of sandboxed applications. After the user selects a file or directory into which a file should breathe saved, Powerbox pokes a hollow in the application sandbox that allows it to execute the specific action.

    A similar mechanism is used to allow access to recently opened files in the "Open Recent" menu, to restore previously open documents when an application is relaunched, to maneuver drag and drop, and so on. The goal is to forestall applications from having to request entitlements that allow it to read and write whimsical files. Oh, and in case it doesn't fade without saying, utter sandboxed applications must breathe signed.

    Here are a few examples of sandboxed processes in Lion, shown in the Activity Monitor application with the fresh "Sandbox" column visible:

    Sandboxed processes in LionSandboxed processes in Lion

    Earlier, the Mac App Store was suggested as a course Apple might expedite the adoption of fresh Lion technologies. In the case of sandboxing, that has already happened. Apple has decreed that utter applications submitted to the Mac App Store must breathe sandboxed, starting in November.

    Privilege separation

    One limitation of sandboxing is that entitlements apply to an entire process. A sandboxed application must therefore possess the superset of utter entitlements required for each feature it provides. As we've seen, the consume of the Powerbox daemon process prevents applications from requiring whimsical access to the file system by delegating those entitlements to another, external process. This is a specific case of the universal principle called privilege separation.

    The concept is to rupture up a knotty application into individual processes, each of which requires only the few entitlements necessary to execute a specific subset of the application's total capabilities. For example, consider an application that needs to play video. Decoding video is a knotty and performance-sensitive process which has historically led to inadequate protection against buffer overflows and other security problems. An application that needs to array video will likely Do so using libraries provided by the system, which means that there's not much a third-party developer can Do to patch vulnerabilities where they occur.

    What a developer can Do instead is insulate the video decoding assignment in its own process with severely reduced privileges. A process that's decoding video probably doesn't requisite any access to the file system, the network, the built-in camera and microphone, and so on. It just needs to accept a stream of bytes from its parent process (which, in turn, probably used Powerbox to gain the faculty to read those bytes from disk in the first place) and recur a stream of decoded bytes. Beyond this simple connection to its parent, the decoder can breathe completely walled off from the rest of the system. Now, if an exploit is organize in a video codec, a malicious hacker will find himself in control of a process with so few privileges that there is puny harm it can Do to the system or the user's data.

    Though this was just an example, the QuickTime Player application in Lion does, in fact, delegate video decoding to an external, sandboxed, extremely low-privileged process called VTDecoderXPCService.

    QuickTime Player with its accompanying sandboxed video decoder processQuickTime Player with its accompanying sandboxed video decoder process

    Another sample from Lion is the Preview application, which completely isolates the PDF parsing code (another historic source of exploits) from utter access to the file system.

    Putting aside the security advantages of this approach for a moment, managing and communicating with external processes is benevolent of a smart for developers. It's certainly less convenient than the traditional approach, with utter code within a solitary executable and no functionality more than a duty summon away.

    Once again in Lion, Apple has provided a fresh set of APIs to inspirit the adoption of what it considers to breathe a best practice. The XPC Services framework is used to manage and communicate with these external processes. XPC Service executables are contained within an application's bundle. There is no installation process, and they are never copied or moved. They must furthermore breathe allotment of the application's cryptographic signature in order to forestall tampering.

    The XPC Service framework will launch an appropriate external process on demand, track its activity, and resolve when to terminate the process after its job is done. Communication is bidirectional and asynchronous, with FIFO message delivery, and the default XPC process environment is extremely restrictive. It does not inherit the parent process's sandbox entitlements, Keychain credentials, or any other privileges.

    The reward for breaking up an application into a collection of least-privileged pieces is not just increased security. It furthermore means that a crash in one of these external processes will not boost down the entire application.

    We've seen this benevolent of privilege separation used to considerable consequence in recent years by Web browsers on several different platforms, including Safari on Mac OS X. Lion aims to extend these advantages to utter applications. It furthermore makes Safari's privilege separation even more granular.

    Safari in Lion is based on WebKit2, the latest and greatest iteration of the browser engine that powers Safari, Chrome, and several other desktop and mobile browsers. Safari in Snow Leopard already separated browser plug-ins such as sparkle into their own processes. (Adobe should not consider this an insult; Apple does the same with its own QuickTime browser plug-in.) As if to further that point, WebKit2 separates the entire webpage rendering assignment into an external process. The number of excuses for the Safari application to crash is rapidly decreasing.

    As the WebKit2 website notes, Google's Chrome browser uses a similar approach to insulate WebKit (version 1) from the rest of the application. WebKit2 builds the separation directly into the framework itself, allowing utter WebKit2 clients to boost advantage of it without requiring the custom code that Google had to write for Chrome. (Check out the process architecture diagrams at the WebKit2 site for more circumstantial comparisons with pre-Lion WebKit on Mac OS X and Chrome's consume of WebKit.)

    Automatic Reference Counting

    Since 2005, I've been very publicly concerned about the long-term prospects of Apple's programming language and application framework, Objective-C and Cocoa, going so far as to speculate about a workable technological exigency a few years in the future.

    When the future arrived, I revisited the issue of Apple's language and API future in light of Apple's theatrical entrance into the mobile market and the unprecedented growth this has enabled. You can read my conclusions for yourself, but the bottom line is that I'm quiet concerned about the issue—and assume Apple should breathe too. Success hides problems, and Apple has been so very successful in recent years.

    Enter (and exit) garbage collection

    Apple has done a tremendous amount of travail to modernize its evolution platform, including completely replacing its compiler, overhauling its IDE, and adding features and fresh syntax to the Objective-C language itself.

    All of these things are great, but not a bit address my specific concerns about recollection management. Apple did eventually descry appropriate to add garbage collection to Objective-C, but my panic that Apple wouldn't really consign to garbage collection in Objective-C turned out to breathe well-founded. Today, years after the introduction of this feature, very few of Apple's own applications consume garbage collection.

    There's a advantageous understanding for this. Runtime garbage collection is simply a penniless appropriate for Objective-C. For utter its syntactic simplicity and long, distinguished history, the C programming language is actually a surprisingly knotty beast, especially when it comes to recollection management. In C, any correctly aligned pointer-size bit pattern in recollection can potentially breathe used as an address; the language explicitly allows casting from void * to a typed pointer, and vice versa. Objective-C, as a superset of C, inherits these charming properties. In exchange for this sacrifice, Objective-C code can breathe compiled alongside modest C code and can link to C libraries with ease.

    This means that the runtime garbage collector is expected to traverse recollection allocated by an whimsical conglomeration of Objective-C and modest dilapidated C code and originate the amend decision—every time—about what recollection may safely breathe collected. Apple's Objective-C garbage collection is a global switch. It can't breathe enabled just for the clean, object-oriented Objective-C code that application developers write; it applies to the entire process, including utter the frameworks that the application links to.

    It seems sensible for garbage collection to boost a hands-off approach to any recollection allocated outside Objective-C's gated object-oriented community. Unfortunately, recollection allocated "the old-fashioned way" in modest C code routinely makes its course into the world of Objective-C, and vice versa. In theory, utter such code could breathe annotated in such a course that it works correctly with garbage collection. In practice, Mac OS X contains course too much code—much of it not written by Apple—to breathe able to properly vet every line of it to ensure that a runtime garbage collector has enough information to originate the birthright decisions in every case.

    And, in fact, despite Apple's bold claims of readiness, there occupy been and continue to breathe cases where even code within Apple's own frameworks can muddle the Objective-C garbage collector. These kinds of bugs are particularly insidious because they may only manifest themselves when the collector runs within a inescapable window of time. The garbage collection compatibility outlook for third-party libraries is even more grim.

    Long chronicle short: garbage collection for Objective-C is out. (It's quiet supported in Lion, but I wouldn't weigh on Apple putting a tremendous amount of exertion into it going forward. And don't breathe surprised if it goes the course of Rosetta in a few years.) In its place, Apple has created something called Automatic Reference Counting, or ARC for short. But to understand ARC, you should first understand how recollection management in Cocoa has traditionally worked.

    Cocoa recollection management

    Cocoa uses a recollection management technique called reference counting. Each demur has a reference weigh associated with it. When some allotment of an application takes ownership of an object, it increments the object's reference weigh by sending it a retain message. When it's done with the object, it decrements the reference weigh by sending a release message to the object. When an object's reference weigh is zero, it is deallocated.

    This allows a solitary demur to breathe used by several different parts of the application, each of which is responsible for bookending its consume of the demur with retain and release messages. If retain is sent to an demur more times than release, then its reference weigh will never gain zero and its recollection will never breathe freed. This is called a recollection leak. If release is sent more times than retain, then a release message sent after the object's reference weigh has reached zero will find itself looking at the region of recollection formerly occupied by the object, which may now hold anything at all. A crash usually ensues.

    Finally, there's the autorelease message which means "release, but later." When an demur is sent an autorelease message, it's added to the current "autorelease pool." When that pool is drained, utter objects in it are sent one release message for each time they were added to the pool. (An demur may breathe added to the same autorelease pool multiple times.) Cocoa applications occupy an autorelease pool that's drained at the discontinuance of each event loop, but fresh pools can breathe created locally by the programmer.

    Simple, right? Just originate certain your retain and release/autorelease messages are balanced and you're golden. But as straightforward as it is conceptually, it's actually surprisingly effortless to find wrong. Experienced Cocoa programmers will divulge you that retain/release recollection management eventually becomes second-nature—and it does—but programmers are only human. Accurately tracking the lifecycle of utter objects in a large application starts to shove the limits of human mental capacity. To help, Apple provides sophisticated developer tools for tracking recollection allocations and hunting down leaks.

    But education and tools only fade so far. Cocoa experts may not descry retain/release recollection management as a problem, but Apple is looking towards the future, towards fresh developers. Other mobile and desktop platforms don't require this sort of manual recollection management in their top-level application frameworks. Based on Apple's past efforts with garbage collection, it seems transparent that Apple believes it would breathe better for the platform if developers didn't occupy to manually manage memory. Now, finally, Apple believes it has organize a solution that it can really find behind.

    Enter ARC

    To understand how ARC works, start by picturing a traditional Objective-C source code file written by an expert Cocoa programmer. The retain, release, and autorelease messages are sent in utter the birthright places and are in impeccable balance.

    Now imagine editing that source code file, removing every instance of the retain, release, and autorelease messages, and changing a solitary build setting in Xcode that instructs the compiler to attach utter the appropriate recollection management calls back into your program when the source code is compiled. That's ARC. It's just what the cognomen says: traditional Cocoa reference counting, done automatically.

    Xcode's ARC setting (highlight added)Xcode's ARC setting (highlight added)

    Before explaining how ARC does this, it's needful to understand what ARC does not do. First, ARC does not impose a fresh runtime recollection model. Code compiled under ARC uses the same recollection model as modest C or non-ARC Objective-C code, and can breathe linked to utter the same libraries. Second, ARC provides automatic recollection management for Objective-C objects only (though note that blocks furthermore happen to breathe Objective-C objects under the covers). recollection allocated in any other course is not touched and must quiet breathe managed manually. (The same goes for other resources dote file handles and sockets.) Finally, ARC is not garbage collection. There is no process that scans the recollection image of a running application looking for recollection to deallocate. Everything ARC does happens at compile time.

    What ARC does at compile time is not magic. There is no abysmal artificial intelligence at travail here. ARC doesn't even consume LLVM's sophisticated static analyzer to device out where to attach the retains and releases. The static analyzer takes a long time to run—too long to breathe a mandatory allotment of the build process; it can furthermore relent unsuitable positives. That's fine for a appliance meant to detect workable bugs, but dependable recollection management requires certainty.

    What allows ARC to travail is the same thing that enables people to (eventually) become expert Cocoa programmers: conventions. Cocoa has rules about the transfer of ownership that takes Place during common operations dote getting or setting an demur attribute, initializing an object, or making a mutable copy. Furthermore, the methods that implement these operations ensue a set of naming conventions. ARC knows utter these rules and uses them to resolve when to retain and when to release.

    In fact, ARC follows the rules in a more scholastic manner than any human ever would, bracketing every operation that could possibly breathe influenced by demur ownership with the appropriate retain and release messages. This can relent a huge number of recollection management operations. Luckily, Apple has an excellent optimizing compiler called Clang (since rechristened by Apple's marketing geniuses as the Apple LLVM Compiler 3.0). Clang sweeps through this sea of mechanically generated code, detecting and eliminating redundancies until what remains looks a lot dote what a human would occupy written.

    Conventions were made to breathe broken, of course. But what ARC lacks in semantic sophistication it makes up for in predictability and speed, speed, speed. In cases where the human really does know best, ARC can breathe told exactly what to Do thanks to a comprehensive set of fresh attributes and macros that allow the developer to annotate variables, data structures, methods, and parameters with specific instructions for ARC. But the concept behind ARC is that these exceptions should breathe rare.

    To ensure that ARC can Do what it's designed to Do in a amend manner, a few additional language restrictions occupy been added. Most of them are esoteric, existing on the boundaries between Objective-C and modest C code (e.g., C structs and unions are not allowed to hold references to Objective-C objects). Compatibility with existing C code is one of Objective-C's greatest strengths. But since ARC is a per-compilation-unit feature and ARC and non-ARC code can breathe mixed freely, these fresh language restrictions originate ARC more dependable without compromising interoperability.

    ARC versus garbage collection

    Apple's Objective-C garbage collection came with some drawbacks. As alluded to earlier, the programmer has puny control over when the garbage collector will run, making demur reclamation non-deterministic. A garbage-collected application with a recollection management bug may crash or not depending on when the collector actually runs. Since garbage collection only runs periodically, the "garbage" (memory) may start to pile up in between runs. This can extend the so-called "high water mark" of an application. Finally, the garbage collection process itself can interfere with the execution of the application.

    Even on a multicore CPU where the collector can flee on a separate thread, it must quiet interact with the running application's recollection image, sometimes (briefly) blocking its progress while it cleans up the garbage. On relatively weak, often single-threaded mobile CPUs, this interference can manifest itself as stutters or glitches in the user interface.

    ARC offers a very different value proposition. To start, it suffers from not a bit of the disadvantages of Objective-C's runtime garbage collection. ARC is deterministic; utter the recollection management code is baked into the executable and does not change at runtime. recollection management is integrated directly into the program flow, rather than being done in batches periodically. This prevents execution stalls, and it can furthermore reduce the lofty water mark.

    Most forms of automatic recollection management incur some benevolent of performance hit. Not ARC. To originate up for any workable extend in the number of recollection management messages generated by ARC, retain and release is 2.5 times faster in Lion; autorelease pools are 6 times faster; and to top it off, balanced Objective-C message sending is 33 percent faster. Furthermore, since it's the compiler, not the programmer, inserting the recollection management code, the generated retain and release code does not occupy to explore exactly dote a balanced compiled Objective-C message send. The compiler has a much more intimate relationship with the Objective-C runtime, and can therefore optimize those operations in ways that a programmer cannot (well, should not, anyway).

    Finally, unlike garbage collection, ARC is a per-compilation-unit setting. Using ARC in your application does not breathe of value that every library you link to will furthermore flee under ARC. This means that you don't occupy to worry about whether or not every solitary one of Apple's libraries works correctly under ARC. Only Apple has to worry about that, and it can resolve on a case-by-case basis which should breathe compiled with ARC and which should not. ARC and non-ARC code can breathe mixed freely.

    Objective-C garbage collection does, however, occupy one leg up on ARC. The garbage collector can detect and correctly reclaim demur graphs with cycles in them. Under reference counting, if demur A has a reference to demur B, and demur B has a reference to demur A, then both A and B occupy a reference weigh of at least one. Even if no other demur in the entire application has a reference to A or B, they will not breathe deallocated when running under ARC because they both, eternally, occupy nonzero reference counts.

    ARC requires the programmer to explicitly maneuver these situations, either manually breaking the cycles by removing one or more references or by using another Objective-C feature called "zeroing weak references." (A weak reference is a reference that doesn't contribute to an object's reference count.) For example, in a typical parent/child relationship, the parent might occupy a reference to the child and the child would occupy a weak reference back to the parent. When the application no longer references the parent or child, the child will occupy a reference weigh of 1 (the parent quiet references it) but the parent will occupy a reference weigh of 0 and will therefore breathe deallocated. That then leaves the child with a reference weigh of 0, and it will breathe deallocated. Et voilà, no recollection leak.

    The "zeroing" allotment means that weak references will breathe set to nil when the demur they reference is deallocated. (Under ARC, utter demur pointers are initially set to zero.) Under balanced circumstances, an demur shouldn't breathe deallocated if there are quiet outstanding references to it. But since weak references don't contribute to an object's reference count, an demur can breathe deallocated when there are outstanding weak references to it. When this happens, the automatic zeroing of the outstanding weak references prevents them from becoming dangling pointers. (In Objective-C, sending a message to nil is a no-op.)

    ARC versus the world

    Now they gain to the 65,536 byte question. Does ARC attach Apple back on an even footing with its competitors when it comes to programming language abstraction? The answer, I'm afraid, is no. ARC takes dependence of almost utter the mundane Objective-C recollection management tasks, but everything outside of Objective-C remains as it was. Furthermore, ARC does very puny to address the other pillar of modern, high-level programming: recollection safety.

    For utter its auto-zeroing pointers and automatic demur deallocation, ARC-enabled Objective-C is quiet a superset of C, and developers remain just a solitary contaminated pointer dereference away from scribbling utter over their application's recollection space. This is a far yowl from the garbage collected, cycle-detecting, memory-safe, and sometimes even dynamically typed languages available on other platforms, both mobile and desktop.

    This brings us back to my six-year-old set of premises: that programming language abstraction increases over time; that Apple's competitors consume languages that occupy a higher plane of abstraction than Objective-C; and that Apple has yet to account for how or when it's going to nigh the gap. ARC may not achieve parity with the likes of Java, C#, and JavaScript, but it does, finally, provide some insight into how Apple plans to hold its evolution platform technologically competitive.

    The first thing ARC reveals is that Apple does correspond that there's a gap to breathe closed. It chose to assault the lowest-hanging fruit first, the one thing about Apple's evolution environment most likely to stand out as primitive and backwards to programmers coming from other platforms or even fresh out of school: manual recollection management. But while doing so, Apple was not willing to sacrifice any of Objective-C's historic strengths. Objective-C with ARC retains its compatibility with existing code and libraries and remains lean, mean, and as fleet as ever—faster, in some cases.

    Right now, Apple seems committed to these two platform pillars: compatibility and performance. Compatibility is essential to protect Apple's considerable investment in its APIs and developer tools. (Apple even went so far as to enable ARC to travail on Snow Leopard, albeit without the zeroing weak references feature.) Performance remains a competitive advantage for Apple's mobile devices, not just in terms of interface responsiveness and stutter-free animations, but furthermore in power usage. Those runtime garbage collectors and virtual machines on other platforms can thrash caches and hold more mobile CPUs cores working longer and harder.

    Apple may occupy danced with runtime garbage collection, but it's going home with compile-time automation. There is no clearer indicator of Apple's commitment than the fact that ARC is now the default for utter fresh projects created in Xcode; garbage collection never was.

    The most intriguing aspect of ARC is what it might portend for Apple's future. ARC shows that Apple is willing to add restrictions to the language in exchange for developer convenience and safety. It furthermore implies that Apple believes that compile-time automation and optimization is, if not preferable to, then at least as advantageous as the runtime solutions available elsewhere, especially on mobile platforms.

    One thing that Apple does not apparently envision in its platforms' future is a traditional virtual machine, for utter the reasons previously stated: performance, compatibility, and power usage. Runtime garbage collection is similarly off the table for now. (It's not that Apple believes that garbage collection necessarily precludes considerable performance; it's just a penniless appropriate for Objective-C and Cocoa.)

    What Apple has instead is a cutting-edge traditional compiler built on a framework that supports many of the same concepts (e.g., bytecode, JIT), but at a lower level.

    Putting it utter together, it's not hard to imagine a future in which Apple's developers write code in a memory-managed, memory-safe language that incorporates only the highest-level aspects of Objective-C, but remains binary compatible with Objective-C libraries and code. This approach has been described as "Objective-C without the C," and that's not far off. They could arrive at this destination through a string of incremental changes—ARC being the latest—which slowly add optional (but recommended) features and restrictions to Objective-C, only the last of which would breathe touted as introducing a "new language."

    Apple has invested a lot of time and manpower in getting off of gcc and onto a faster, more capable compiler. Now that the transition is over, Apple's attention can revolve towards adding innovative features. The next few years of WWDC could breathe interesting.

    The condition of the file system

    The file system implementation is not something most Mac users assume about—nor should they. But dote any other allotment of an operating system, there's some expectation that it will better over time. And dote any piece of technology, there comes a point where incremental improvements are no longer enough and a fresh start is required.

    Mac OS X itself was one such fresh start, albeit one derived from an existing product that was only slightly newer than the one it was replacing. But Mac OS X's file system, HFS+, was carried over from classic Mac OS directly into Mac OS X. It didn't find a fresh start when the rest of the OS did.

    Hopes were lofty for a fresh file system back in 2006 when Apple publicly declared its interest in a port of Sun's innovative ZFS file system. The next year, Sun's CEO announced that ZFS would breathe allotment of Mac OS X 10.5 Leopard—obviously without consulting Apple first.

    It didn't happen; Leopard shipped with HFS+. Two years after that, in 2009, Apple itself listed ZFS as a feature of Snow Leopard Server, only to later remove utter references to ZFS from its Snow Leopard webpages. A few months later, Apple shut down its open-source project to port ZFS to Mac OS X.

    In the meantime, HFS+ has certainly been incrementally improved. Apple has added support for metadata journaling, case sensitivity, access control lists, and arbitrarily extensible metadata. not a bit of these additions changed the basic design of the file system, however. HFS+ is thirteen years old, and is itself an extension of the HFS file system which is more than twenty-five years old. The condition of the expertise in file system design has advanced a lot since 1985.

    But again, most people don't expend much time thinking about the file system. They assume about files and folders, sure, but not the software that manages how the individual bytes are arranged on the storage device. My longstanding preoccupation with the nitty-gritty of file storage has often been met with indifference or even derision. "Who cares about a fresh file system?" inquire the scoffers. "HFS+ works fine. It stores and retrieves my files just fine. What's the problem?"

    In response to this sentiment, I'd dote to proffer some concrete reasons why HFS+ is long overdue for replacement. I believe that Apple understands these problems better than anyone, but that a string of unfortunate events has resulted in its next-generation operating system being hamstrung with a previous-generation file system for the past decade. Before discussing whether or not Lion makes any progress in this area, let's boost a hard explore at their dilapidated friend, HFS+.

    What's wrong with HFS+

    Software is written with inescapable target hardware in mind. When HFS was created, the top-of-the-line Macintosh came with an 800K floppy drive, the "high-end" storage offered by Apple was a 20MB hard drive the size of a lunchbox, and the CPU was from the Motorola 68000 family. Thirteen years later, HFS+ replaced HFS, the floppy disks were 1.44MB, and Apple's hard drives topped out around 6GB. hold this context in intelligence as they consider the following details of HFS+'s implementation.

    When searching for unused nodes in a b-tree file, Apple's HFS+ implementation processes the data 16 bits at a time. Why? Presumably because Motorola's 68000 processor natively supports 16-bit operations. Modern Mac CPUs occupy registers that are up to 256 bits wide.

    All HFS+ file system metadata read from the disk must breathe byte swapped because it's stored in big-endian form. The Intel CPUs that Macs consume today are little-endian; Motorola 68K and PowerPC processors are big-endian. (The performance cost of this is negligible; it's mostly just silly.)

    The time resolution for HFS+ file dates is only one second. That may occupy been enough a few decades ago when computers and disks were slower, but today, many thousands of file system operations (and many billions of CPU cycles) can breathe executed in a second. Modern file systems occupy up to nanosecond precision on their file dates.

    File system metadata structures in HFS+ occupy global locks. Only one process can update the file system at a time. This is an embarrassment in an age of preemptive multitasking and 16-core CPUs. Modern file systems dote ZFS allow multiple simultaneous updates, even to files that are in the same directory.

    The total number of blocks in an HFS+ volume is stored in a 32-bit value. With 4KB blocks, this allows for a maximum disk size of 17TB. That may sound huge to you now, but consider that it's only a sixfold extend over what they occupy today, and today's largest hard drives are, in turn, a sixfold extend over what they had in 2005. (Apple can, of course, extend the screen size from 4KB to, say, 8KB, but you can only play that game so long.)

    HFS+ lacks sparse file support, which allows space to breathe allocated only as needed in large files. assume about an application that creates a 1GB database file, then writes a few bytes at the start as a header and a few bytes at the discontinuance as a footer. On HFS+, slightly less than a gigabyte of zeros would occupy to breathe written to disk to originate that happen. On a modern file system with sparse file support, only a few bytes would breathe written to disk.

    Concurrency, metadata written in the amend byte order, sub-second date precision, support for massive volume sizes, and sparse file support are utter common features of Unix file systems. Mac OS X, of course, is built on a Unix foundation. When HFS+ was ported from classic Mac OS to Mac OS X, it needed to breathe extended to support some minimum set of features that are expected from Unix file systems.

    Some of those features were an effortless fit, but others were very difficult to add to the file system without breaking backwards compatibility. One particularly scary sample is the implementation of hard links on HFS+. To hold track of hard links, HFS+ creates a separate file for each hard link inside a hidden directory at the root plane of the volume. Hidden directories are benevolent of creepy to commence with, but the actual scare comes when you recollect that Time Machine is implemented using hard links to avoid unnecessary data duplication.

    Listing the contents of this hidden directory (named "HFS+ Private Data", but with a bunch of non-printing characters preceding the "H") on my Time Machine backup volume reveals that it contains 573,127 files. B-trees or no b-trees, over half a million files in a solitary directory makes me nervous.

    That sentiment is compounded by the most glaring omission in HFS+—and, to breathe fair, many other file systems as well. HFS+ does not concern itself with data integrity. The underlying hardware is trusted implicitly. If a few bits or bytes find flipped one course or the other by the hardware, HFS+ won't notice. This applies to both metadata and the file data itself.

    Data corruption in file system metadata structures can render a directory or an entire disk unreadable. (For a double-whammy, assume about corruption that affects the "HFS+ Private Data" directory where every solitary hard link file on a Time Machine volume is stored.) Corruption in file data is arguably worse because it's much more likely to fade undetected. Over time, it can propagate into utter your backups. When it's finally discovered, perhaps years later when looking at dilapidated baby pictures, it's too late to Do anything about it.

    But how often does data corruption actually occur? The retort seems to breathe "more often than you'd think." Here's an excerpt from a 2010 academic paper on data integrity:

    In a recent study of 1.53 million disk drives over 41 months, Bairavasundaram et al. account for that more than 400,000 blocks had checksum mismatches, 8 percent of which were discovered during RAID reconstruction, creating the possibility of actual data loss. They furthermore organize that nearline disks develop checksum mismatches an order of magnitude more often than enterprise class disk drives.

    Read the whole paper (PDF) for more detail and references. (Here's another sample [PDF] from CERN, and the data integrity section of the ZFS Wikipedia entry contains more information and links.)

    Most of these studies concern themselves with enterprise-scale deployments, but personal storage consume today is where enterprise storage was only a few years ago (in terms of capacity, if not throughput). And hold in intelligence that utter of these issues only find worse as the data volume goes up—which it inevitably does, year after year.

    It's rapidly becoming inexcusable for the storage systems they entrust with some of their most precious possessions—something we're actively encouraged to Do by Apple itself—to boost such a cavalier approach to data integrity. The worst allotment is that there's puny a user can Do to originate up for this technological gap; backups only serve to silently spread data corruption.

    I'll quit here, but Do note that I haven't even gotten to many of the other headliner features of modern file systems: constant-time snapshots, transactional updates, data deduplication, and on and on. HFS+ has served Apple well, and probably for far longer than its designers ever imagined it would. But dote utter the other Apple-related products and technologies that appropriate this description (e.g., classic Mac OS, Carbon, PowerPC), there comes a time when things once treasured must pass from this world.

    File system changes in Lion

    Finally, they gain to the heart of the matter. In Lion, what does Apple roar to the god of file system death? "Not today."

    That's right, the default and only file system on which you can install Lion is their dilapidated friend, HFS+. As noted earlier, I'm certain Apple is acutely awake of HFS+'s shortcomings and would weigh its inability to territory a successor among its (rare) recent failings as steward of the platform. But it looks dote it will boost a while longer for Apple's file system roadmap to find back on track after the ZFS near-miss.

    Nevertheless, there are some file system changes in Lion—some significant ones, in fact. The biggest is the introduction of Apple's first actual crack at creating a rational volume manager: Core Storage.

    In earlier versions of Mac OS X (or classic Mac OS, for that matter), a solitary physical disk could hold one or more volumes. That is, connecting the disk to a Mac would understanding one or more fresh hard drive icons to appear in the Finder. By far, the most common case is to occupy just one volume on each physical hard drive. But Mac users with more knotty needs (e.g., people who occupy to install many different versions of the operating system for testing or review purposes) boost complete advantage of the faculty to carve up a solitary physical disk into multiple independent volumes.

    The role of HFS+ in this amalgamate is revealed by Apple's nomenclature. HFS+ is a "volume format." It stands to understanding that there must then breathe something above HFS+ responsible for managing the multiple volumes that may exist on a solitary disk, in the same course that HFS+ manages the multiple files and folders that exist within a solitary volume. And so there is. Apple supports several varieties of what it calls "partition maps." ("Partitions" are the regions of a solitary disk carved out for volumes, one volume per partition. Apple's currently favored partition map is the GUID flavor.)

    Logical volume management is a broad term that usually means allowing more flexible relationships between disks and volumes than traditionally provided by partition maps. In the case of Apple's Core Storage, the key fresh feature is the faculty for a solitary volume to span multiple physical disks.

    Somewhat obscuring this is a raft of fresh terminology to delineate the fresh layers of the storage stack. At the very top plane is the rational Volume Group, which may hold one or more Physical Volumes. A Physical Volume provides storage; it may breathe a solitary physical disk, a disk image file, or even a RAID device. A rational Volume Group exports zero or more rational Volume Families. A rational Volume Family contains one or more rational Volumes, each of which presents a blank canvas onto which—finally!—a volume format dote HFS+ may reside.

    Got utter that? Don't worry if you haven't. The only thing you requisite to understand for now is that Core Storage provides a much richer set of abstractions above the volume format. The next question is obvious: what does Lion Do with Core Storage?

    If you're entertaining visions of ZFS-style pooled storage, let me nip that in the bud. There is no friendly GUI for creating disk-spanning volumes, and the command-line tools provided are rudimentary and, in my brief testing, don't look to support utter of the features ostensibly enabled by Core Storage.

    Core Storage's purpose in Lion is discreetly hidden in the rational Volume Family tier of the layer cake. rational Volume Families don't just export rational Volumes, they furthermore hold properties that apply to them. One such set of properties in Lion enables complete disk encryption.

    Though Apple is using the cognomen FileVault to brand this feature, it has absolutely nothing to Do with the feature of the same cognomen from earlier versions of Mac OS X. The earlier incarnation of FileVault encrypted an individual user's home directory by storing it in an encrypted disk image file. This presented utter sorts of complications to common operations, and FileVault earned a horrible reputation for penniless compatibility with existing software (including Apple's own, dote Time Machine).

    Lion's FileVault doesn't just encrypt users' home directories, and it doesn't consume encrypted disk image files. Instead, it's Apple's implementation of whole disk encryption. This means that every byte of data that makes up the volume is encrypted. Furthermore, this encryption is completely transparent to utter software (including the implementation of HFS+ itself) because it takes Place at a layer above the volume format—a layer that application software does not descry at all.

    Having used a third-party whole-disk encryption product for years, I can divulge you that this approach works amazingly well. It really is completely transparent, and the only compatibility issues I've had involved operating system upgrades. (When affecting from Leopard to Snow Leopard, a fresh version of the disk encryption software was required. Presumably, this will not breathe a problem now that the feature is built into the OS.)

    Enabling whole-disk encryption is effortless in Lion. The FileVault tab in the Security & Privacy preference pane carefully guides a user through the process, presenting transparent explanations along with an extremely generous dose of caution.

    FileVault whole-disk encryptionFileVault whole-disk encryption

    Each user who will breathe able to decrypt the drive must enter their password to Do so. Next, an auto-generated "recovery key" is presented, along with a suggestion to "make a copy and store it in a safe place." This is a last revolve in case a user forgets his or her account password. More dire warnings about data loss conduct this information.

    FileVault recovery key: your last best hopeFileVault recovery key: your last best hope

    Will people really write down that long recovery key and store it in a safe place? Apple has its doubts, it seems, because the next screen asks if you'd dote Apple to store the recovery key for you. There is no default altenative for this question, which is exactly right, as far as I'm concerned. Most users probably should allow Apple to store their recovery key, but making that the default might breathe seen as an overreach by geeks and security nerds.

    If you pick to dependence Apple, you must enter answers to three personal questions of your choice. The dialog claims that no one, not even Apple itself, can access your recovery password without the answers to these questions. We've heard claims dote this before, but I'm inclined to believe that Apple has learned from the mistakes of others.

    Recovery key escrow:  back Apple  back youRecovery key escrow: back Apple back you

    Finally, Apple insists that a recovery partition breathe present on the disk that's about to breathe encrypted. If it isn't, and if one can't breathe created (e.g., because it uses the wrong benevolent of partition map, or because doing so would shift a Boot Camp partition to the fourth position, making it unbootable), encryption won't breathe allowed to proceed. (It's benevolent of annoying that this check is only made at the very discontinuance of the process.)

    Assuming a recovery partition exists or can breathe created, a restart is required to enable encryption. Upon reboot, a screen that looks a lot dote the Lion login screen (but only containing the users who are allowed to decrypt the volume) appears instantly. Select a user and enter the amend login password and the actual boot process begins. Even if auto-login is disabled, you will boot directly into the account whose password was just entered.

    Revisiting the FileVault preference pane shows an estimate of the time remaining before the encryption process is complete. Encryption happens transparently in the background, which is a advantageous thing because it takes a long time. While it's running, you can consume applications, logout, reboot, and generally consume your Mac as you normally would without perturbing the encryption process.

    If any users on the system are unable to decrypt the disk, they can breathe allowed to Do so by having them enter their login password.

    Enable more users to access the encrypted diskEnable more users to access the encrypted disk

    The output of the diskutil list command now looks a bit outlandish (compare to earlier):

    /dev/disk1 #: sort cognomen SIZE IDENTIFIER 0: GUID_partition_scheme *250.1 GB disk1 1: EFI 209.7 MB disk1s1 2: Apple_CoreStorage 124.5 GB disk1s2 3: Apple_Boot Recovery HD 654.6 MB disk1s3 4: Apple_HFS Timex 124.6 GB disk1s4 /dev/disk2 #: sort cognomen SIZE IDENTIFIER 0: Apple_HFS Lion Ex *124.2 GB disk2

    What once appeared to the OS as a solitary disk device now registers as two. One contains the two non-encrypted volumes (Recovery HD and Timex) plus the fresh Core Storage volume, and the other contains the mounted incarnation of the newly encrypted (well, encrypting, in this case) volume. Using the special Core Storage variant of the list command (diskutil cs list) reveals more detail, most of which should now originate sense after the earlier terminology review.

    CoreStorage rational volume groups (1 found) | +-- rational Volume Group 19566D89-E29A-4C6C-88FA-6B845EF1DEBB ========================================================= Name: Lion Ex Sequence: 1 Free Space: 0 B (0 B) | +-< Physical Volume 1A645A01-E149-48B4-8C79-5FD3E20384F1 | ---------------------------------------------------- | Index: 0 | Disk: disk1s2 | Status: Online | Size: 124509331456 B (124.5 GB) | +-> rational Volume Family 58B532AA-B265-4AC7-B53B-12BB039D97B2 ---------------------------------------------------------- Sequence: 9 Encryption Status: Unlocked Encryption Type: AES-XTS Encryption Context: Present Conversion Status: Converting Has Encrypted Extents: Yes Conversion Direction: forward | +-> rational Volume 8A7ACC28-321B-4653-8E85-94CAF047D1DE --------------------------------------------------- Disk: disk2 Status: Online Sequence: 4 Size (Total): 124190560256 B (124.2 GB) Size (Converted): 2539913216 B (2.5 GB) Revertible: Yes (unlock and decryption required) LV Name: Lion Ex Volume Name: Lion Ex Content Hint: Apple_HFS

    Lion doesn't originate encrypting disks other than the boot disk particularly easy. The Disk Utility application can remove encryption from a volume, change a volume's encryption password, or reformat a volume with encryption enabled (deleting utter the data currently on the volume in the process), but there is no option to transparently encrypt a volume without erasing it.

    Command-line tools to the rescue: diskutil will happily attempt to encrypt any volume you point it at, without erasing it first. Actually, the process is to transform it to a Core Storage volume which may optionally involve encryption. Let's encrypt the Timex volume, shown as disk1s4 in the earlier diskutil list output.

    % diskutil cs transform disk1s4 -passphrase mysecret Started CoreStorage operation on disk1s4 Timex Resizing disk to appropriate Core Storage headers Creating Core Storage rational Volume Group Attempting to unmount disk1s4 Switching disk1s4 to Core Storage Waiting for rational Volume to appear Mounting rational Volume Core Storage LVG UUID: B02B86AC-C487-43B3-8C2E-7918CE80ECDF Core Storage PV UUID: 76336EBE-A3B5-4E1E-98B4-8A6873746D86 Core Storage LV UUID: E1F2E293-9952-425E-A597-0954BA734102 Core Storage disk: disk3 Finished CoreStorage operation on disk1s4 Timex Encryption in progress; consume `diskutil coreStorage list` for status

    As the command output indicates, the volume is shrunk slightly to accommodate the Core Storage headers, then the layer cake of rational volume management components is created, at the very bottom of which is the fresh rational volume. No restart is required to commence the process, which happens transparently in the background just dote the one initiated from the GUI. The diskutil cs list command now shows a pair of rational Volume Groups, each of which is declared to breathe in the process of encryption. The exact amount of data encrypted and remaining to breathe encrypted on each volume is furthermore listed.

    CoreStorage rational volume groups (2 found) | +-- rational Volume Group 19566D89-E29A-4C6C-88FA-6B845EF1DEBB | ========================================================= | Name: Lion Ex | Sequence: 1 | Free Space: 0 B (0 B) | | | +-< Physical Volume 1A645A01-E149-48B4-8C79-5FD3E20384F1 | | ---------------------------------------------------- | | Index: 0 | | Disk: disk1s2 | | Status: Online | | Size: 124509331456 B (124.5 GB) | | | +-> rational Volume Family 58B532AA-B265-4AC7-B53B-12BB039D97B2 | ---------------------------------------------------------- | Sequence: 9 | Encryption Status: Unlocked | Encryption Type: AES-XTS | Encryption Context: Present | Conversion Status: Converting | Has Encrypted Extents: Yes | Conversion Direction: forward | | | +-> rational Volume 8A7ACC28-321B-4653-8E85-94CAF047D1DE | --------------------------------------------------- | Disk: disk2 | Status: Online | Sequence: 4 | Size (Total): 124190560256 B (124.2 GB) | Size (Converted): 16999776256 B (17.0 GB) | Revertible: Yes (unlock and decryption required) | LV Name: Lion Ex | Volume Name: Lion Ex | Content Hint: Apple_HFS | +-- rational Volume Group B02B86AC-C487-43B3-8C2E-7918CE80ECDF ========================================================= Name: Timex Sequence: 1 Free Space: 0 B (0 B) | +-< Physical Volume 76336EBE-A3B5-4E1E-98B4-8A6873746D86 | ---------------------------------------------------- | Index: 0 | Disk: disk1s4 | Status: Online | Size: 124551483392 B (124.6 GB) | +-> rational Volume Family F02B9A32-10DE-4BDF-9697-00CE1B6F1133 ---------------------------------------------------------- Sequence: 6 Encryption Status: Unlocked Encryption Type: AES-XTS Encryption Context: Present Conversion Status: Converting Has Encrypted Extents: Yes Conversion Direction: forward | +-> rational Volume E1F2E293-9952-425E-A597-0954BA734102 --------------------------------------------------- Disk: disk3 Status: Online Sequence: 4 Size (Total): 124232712192 B (124.2 GB) Size (Converted): 94633984 B (94.6 MB) Revertible: Yes (unlock and decryption required) LV Name: Timex Volume Name: Timex Content Hint: Apple_HFS

    At any point, the encryption process can breathe reversed (using Disk Utility, the FileVault tab of the Security & Privacy preference pane, or the diskutil command-line program). The decryption process furthermore happens in the background.

    Changing the encryption password for a disk does not require a lengthy decryption and re-encryption process. I assume FileVault in Lion works dote other whole disk encryption solutions in that what the password actually unlocks is the actual encryption key for the volume. Changing the encryption password only requires decrypting and re-encrypting the actual encryption key, which is tiny.

    The encryption features that Apple has chosen to provide access to in the GUI betray a lot about the objective of this feature. First, it's meant to breathe completely transparent. The only change as far as the user is concerned is that the login screen appears to occupy moved to the very beginning of the startup process. There is no separate password to remember; the user's login password decrypts the disk. The same goes for every other user with an account on the system.

    Login passwords are only tied to a boot disk, however. Using login passwords to encrypt disks that may skedaddle from one Mac to another could lead to confusion. This partly explains why there's no GUI option for encrypting non-boot disks. The other allotment of that decision is likely that FileVault is focused on mobile users. not a bit of Apple's laptops occupy more than one internal drive, and partitioning is rare and probably only done by users who furthermore know enough to explore up the command-line utility to enable disk encryption on their non-boot volumes.

    Transparent encryption and decryption, impeccable software compatibility, a friendly GUI with ample safety nets for non-geek users—what's not to love? Ah, I'm certain you're wondering about performance. utter forms of whole disk encryption capitalize from the current imbalance between CPU power and disk speed. In almost utter circumstances, the CPU in your Mac spends most of its time twiddling its thumbs with nothing to do. This is especially suitable for operations that involve a lot of disk access.

    Whole disk encryption takes advantage of this nearly omnipresent CPU cycle glut to sneak in the tiny chunks of travail it requires to encrypt and decrypt data from the disk. Apple furthermore leverages the special-purpose AES instructions and hardware on Intel's newest CPUs, further reducing the CPU overhead. The discontinuance result is that regular users will breathe hard-pressed to notice any reduction in performance with encryption enabled. Based on my experience with the feature in prerelease versions of Lion, I would strongly consider enabling it on any Mac laptop I strategy to travel with.

    File system future

    Disk encryption that actually works, plus some basic rational volume management features—that's utter well and good. But where does this leave us on the file system front? Perhaps things are not as contaminated as they seem. The following is utter speculation, but given Apple's information vacuum on utter things file-system-related, it's utter I've got for now.

    Core Storage is probably the most significant file system change in the history of Mac OS X. Let's assume about what it does. Core Storage is responsible for managing the chunks of data that originate up the individual rational volumes on a disk. To Do so, presumably it has a set of metadata structures for tracking allocated and free space and for remembering which chunks belong to which volumes.

    Now imagine that those chunks commence to shrink until they are the size of, say, individual files. And instead of volumes, imagine those file-sized chunks belonging to directories. Okay, it's a stretch, but again, it's utter they occupy to fade on. Assuming Apple is pleased with the course Core Storage turned out, it has effectively fielded its first brand-new code that performs some of the same basic functions as a file system. Were Apple so inclined, it seems technically plausible, at least, that it could extend this travail into a fresh in-house file system project.

    With ZFS out of the picture, Btrfs presumably eliminated due to its licensing, and future evolution of ReiserFS uncertain, its hard to descry where Apple will find the modern file system that it so desperately needs other than by creating one itself.

    This is something I've been anticipating for years. I would occupy certainly welcomed ZFS with open arms, but I was equally confident that Apple could create its own file system suited to its particular needs. That confidence remains, but the ZFS distraction may occupy added years to the timetable.

    In the meantime, a few plucky souls are quiet determined to bring ZFS to Mac OS X. I wish them luck, but I would much prefer a solution supported by the operating system vendor. Apple, the gauntlet has been thrown down; it's time to deliver.

    Document revisions

    Lion's modernized document model leans heavily on the faculty to manage multiple versions of a solitary document. Viewed solely through the user interface, it appears to breathe magic. Unlike earlier incarnations of autosave, you won't descry auto-generated files appearing and disappearing alongside the original document. But the data obviously has to breathe stored somewhere, so where is it?

    Despite utter its flaws, the Mac OS X file system does occupy several features that might breathe useful for saving multiple versions of files. Version number metadata could breathe stored in an extended attribute; the file data itself could conceivably breathe stored in named forks; the existing invisibility metadata could breathe used to camouflage the multiple versions.

    Although Apple has gotten religion regarding file system metadata in recent years, leaning heavily on extended attributes in the implementation of Time Machine, downloaded file quarantines, and access control lists, metadata holdovers from classic Mac OS are quiet out of favor. If Spotlight's implementation has taught us anything, it's that today's Apple prefers to hold things simple when it comes to the file system.

    Given utter of this, I wasn't surprised to find a /.DocumentRevisions-V100 directory lurking at the root plane of my boot drive, birthright alongside the /.Spotlight-V100 directory. Inside, you'll find an SQLite database file (/.DocumentRevisions-V100/db-V1/db.sqlite) containing tables for tracking files, the individual versions of those files (which Apple calls "generations"), and the storage location of the data. Here's the schema, for the curious.

    CREATE TABLE files ( file_row_id INTEGER PRIMARY KEY ASC, file_name TEXT, file_parent_id INTEGER, file_path TEXT, file_inode INTEGER, file_last_seen INTEGER NOT NULL DEFAULT 0, file_status INTEGER NOT NULL DEFAULT 1, file_storage_id INTEGER NOT NULL ); CREATE TABLE generations ( generation_id INTEGER PRIMARY KEY ASC, generation_storage_id INTEGER NOT NULL, generation_name TEXT NOT NULL, generation_client_id TEXT NOT NULL, generation_path TEXT UNIQUE, generation_options INTEGER NOT NULL DEFAULT 1, generation_status INTEGER NOT NULL DEFAULT 1, generation_add_time INTEGER NOT NULL DEFAULT 0, generation_size INTEGER NOT NULL DEFAULT 0 ); CREATE TABLE storage ( storage_id INTEGER PRIMARY KEY ASC AUTOINCREMENT, storage_options INTEGER NOT NULL DEFAULT 1, storage_status INTEGER NOT NULL DEFAULT 1 );

    Unlike Time Machine, Apple's file version storage system is not limited to saving a complete copy of each fresh revision of a file. A second SQLite database (/.DocumentRevisions-V100/.cs/ChunkStoreDatabase) tracks the individual chunks that disagree from one revision of a file to another. (Examining its schema is left as an exercise for the reader. Just recollect to copy the database file to a fresh location and flee the sqlite3 program on the copy instead of the actual database, which will likely breathe locked anyway.)

    Intelligently splitting files into chunks such that only a few chunks change from one revision to another is actually quite a difficult problem. consider a 10MB file, initially split into ten 1MB chunks. Now imagine that the next revision of the file simply adds two bytes to the very beginning of the file. Were the fresh revision to breathe naïvely split into ten equal-sized chunks, every chunk would breathe different from utter previously created chunks, defeating the entire purpose of splitting files into chunks rather than saving complete copies every time.

    One technique Apple uses to deal with this problem is called Rabin fingerprinting. Chunks of the file are selected based on their content, rather than strictly based on their offset within the file. (The title of the research paper that introduced this technique, A Low-bandwidth Network File System, suggests that it might furthermore breathe useful for, say, a network-based file storage system. Hmmm.)

    This algorithm is not blindly applied to every file, however. The chunk storage engine knows about the internal structure of many common file formats (e.g., JPEG images, MPEG4 video, PDFs) and can intelligently chunk them based on this knowledge, separating headers and footers, finding the borders between internal elements, and so on. Unlike Spotlight, there doesn't appear to breathe a plug-in system for adding specific support for fresh file types. Custom file types saved by third-party applications appear to breathe left to the whims of Rabin fingerprinting.

    Very little files (under, say, 32KB) appear not to breathe chunked at all. Chunking is not guaranteed to happen immediately when a file is saved; it may happen at a later time. Very large files are generally split into larger pieces, preventing a situation where a 2GB file produces thousands of chunks. This whole account for is flee by a new, private GenerationalStorage.framework which includes a daemon named revisiond.

    (There's an tantalizing break here for a third-party developer to create an "unauthorized" application for browsing the contents of the generation store, perhaps even hacking in a fresh context menu particular in the Finder for listing previous revisions of a selected file. An application dote this probably won't breathe allowed into the Mac App Store, and it's likely to rupture in the next OS revision, but it may quiet find enough customers to breathe worthwhile.)

    Apple's generational storage system is an tantalizing amalgamate of tried-and-true technologies (SQLite, daemons, modest files and directories) with just enough cleverness to avoid being an undue tribulation to the system in operation. And remember, every solitary file created on the system is not automatically versioned in Lion. Generational storage is a feature that developers must explicitly use. I certain hope a lot of them Do so.

    Resolution independence

    Resolution independence has been "coming soon to Mac OS X" since 2005. The dream of drawing the same interface elements at the same visible size but with more pixels was so nigh in 2007 that they could savor it. Then Snow Leopard arrived and the Mac's interface scalability features actually regressed. Depressing.

    Meanwhile, Mac OS X's sibling operating system waltzed birthright into a high-resolution UI on its very first try. iOS's secret? Don't try to support whimsical scale factors, just support one: double resolution. A 50x50-pixel square on a non-retina iPhone screen is exactly the same size as a 100x100-pixel square on a retina display. Graphics that occupy not been updated for the higher resolution are simply drawn with four-pixel squares in Place of each low-resolution pixel. utter dimensions are nice, even, integer multiples of each other. This is a impeccable appropriate for physical screens which, of course, occupy an integer number of pixels. Fractional measurements necessarily require grim compromises.

    Lion has taken the hint from its younger brother. whimsical scalability is gone. In its Place is a solitary check box to enable "HiDPI" array modes. (This option is quiet hidden away in the Quartz Debug application, so it's clearly not an end-user feature. But unlike utter previous incarnations of resolution independence, this one actually works.)

    HiDPI  array modes on a 15-inch MacBook Pro (native resolution: 1440x900)HiDPI array modes on a 15-inch MacBook Pro (native resolution: 1440x900)

    After enabling HiDPI, fresh array modes will become available. In the screenshot above, the 720x450 mode is half endemic screen dimensions, and the 640x400 mode is half the (non-native) 1280x800 setting. After selecting a HiDPI mode, everything is drawn with twice as many pixels as its non-HiDPI equivalent. Here's a screenshot featuring TextEdit, their customary interface scalability workhorse.

    TextEdit running in Lion's "HiDPI" mode Enlarge / TextEdit running in Lion's "HiDPI" mode

    It looks pretty good, right? The only flaws are the bitmap graphics that haven't been updated for HiDPI (look closely at the black triangles in the ruler). Unfortunately, there are a lot of these throughout the operating system and its bundled applications. But unlike in utter years past, the framework is finally there for third-party developers and Apple itself to finally find their applications ready for a world in which 300-dpi desktop and laptop displays are more than just expensive curiosities.

    Unlike iOS, Mac OS X has to contend with a much wider variety of array sizes. Thus far, there has been no Mac equivalent of the iPhone 4, arriving with a double-density array and quickly selling so many units that it represents a significant portion of the installed base. Still, the ease with which iOS developers adapted to the retina array gives me confidence that this pixel-doubling approach can travail on the Mac as well. They just occupy to wait a bit longer. By now, they should breathe used to it.

    Applications

    Thanks to the comprehensively revised user interface, most applications that ship with Lion explore new, but a few of them occupy particularly significant changes. I'm not going to cover utter of them (you'll find more extensive screenshot galleries elsewhere), but here are some highlights.

    The Finder

    The Finder's transition from Carbon to Cocoa in Snow Leopard is starting to pay off in Lion. Several fresh APIs added to Cocoa in Lion occupy been adopted by the Finder. In days past, when the Finder was quiet a Carbon application, it rarely got the latest and greatest features at the same time as other bundled applications. No more.

    Cocoa in Lion gives developers more control over the image displayed when an particular is dragged from one Place to another. The Lion Finder uses this control to transform multi-item selections from the customary ghostly image of the source into a compressed, realigned, list-view representation. This transformation happens a minute or two after the drag begins.

    While this is a fine demonstration of a fresh API, the experience is a bit off-putting. Imagine taking a dish out of the dishwasher and then having it start flopping around dote a fish in your hand. This is a rare case of Apple losing sight of what's needful in real-time interaction design. Stability and responsiveness lead to comfort. A transformative animation (instability) that happens after a short retard (the appearance of unresponsiveness) does not originate for advantageous experience. I prodigy how many novice users will instinctively release the mouse button and inadvertently terminate the drag operation the first time this animation is triggered.

    Search tokensSearch tokens

    The Finder furthermore proudly demonstrates Lion's fresh capsule-style search tokens. Free text can breathe entered into the search territory as usual, but a pop-up menu provides options to confine the scope of the search terms typed so far. The only two options available are "Filename" and "Everything," but the interface is fun and effortless to use, and the potential is there for much more sophistication. (For more knotty searches, the full-fledged Spotlight search with nested boolean logic remains in Lion.)

    By default, at the top of the Lion Finder's sidebar is the fresh "All My Files" item. It's a canned search that finds utter documents in the user's home directory and displays the results in a flat list. The sidebar particular representing the computer as a whole, showing utter attached drives and connected servers, is quiet available, but is not in the sidebar by default. The same goes for the home directory item. The other predefined saved searches (e.g., Today, Yesterday, utter Images, etc.) are no longer available, though they can breathe recreated manually.

    All My Files combined with a secondary filter, arranged by kindAll My Files combined with a secondary filter, arranged by kind

    The addition and prominence of "All My Files" is yet another vote of no-confidence in the user's faculty to understand and navigate the file system. If you've ever seen a Mac user try to navigate from the top plane of his hard drive down to his Documents folder, you can commence to understand the challenge Apple is up against here. The "All My Files" particular is just what the doctor ordered. In the increasingly rare cases when novices consume the Finder directly, rather than managing their data from within an application dote iTunes or iPhoto, utter they want to know is, "Where are utter my files?" Asked and answered.

    Expert users with thousands upon thousands of files will likely find the "All My Files" feature less useful. But if you quit thinking of it as a "location" and start thinking of it as a saved search to which you can apply additional filters with the toolbar's search field, it starts to find more interesting. The only remaining barrier is performance, which does suffer as the number of files increases.

    All of the existing Finder view styles (icon, list, column, and cover flow) support a fresh "Arrange By" option which sorts items into groups. Each group has a header which "sticks" to the top of the window as the view is scrolled, until the last particular belonging to that group scrolls off the top of the list. The columns in the group headers are frustratingly un-configurable and can't breathe individually resized. But those quibbles aside, the feature does add an tantalizing fresh dimension to file browsing.

    A fresh sort order has furthermore been added to utter views: Date Added. This is an model order for the Downloads folder. Sorting by creation or modification date was always problematic for files that preserved their timestamps through the download process (e.g., zip-compressed Mac applications). This would understanding "new" downloads to appear in unexpected positions in the list. I'm tempted to declare Date Added sorting as best fresh feature in the Finder, but I'm apprehensive that might look dote damning with faint praise.

    Aesthetically speaking, the Finder, dote the rest of Lion, has been visited by the color vampire. The Finder sidebar doesn't even homage custom folder icons, showing them as generic gray folders instead. That seems a puny tyrannical, even for Apple.

    The only  advantageous folder is a gray folderThe only advantageous folder is a gray folder

    This paternalism extends to other aspects of the Finder, as well. Library folders are now invisible in the Finder, removing the temptation for novice users to fade mucking around in directories they don't understand. The "Go to Folder…" menu command quiet exists, so customer support has some way, at least, to find users there without resorting to a shell prompt. But existing support documents that involve instructions and screenshots that await the Library folder to breathe visible will occupy to breathe revised for Lion.

    View optionsView options

    The Finder's destructive amalgamate of browser and spatial behaviors remains in Lion. The tradition of subtly changing the rules that govern when, where, and how view condition changes are applied and honored furthermore continues. Just in case anyone thought they had finally figured out how the Snow Leopard Finder decides what view to account for when displaying the contents of a folder in a particular window, Lion changes the rules again.

    The controls at the top of the view options palette now involve a arcane sub-checkbox labelled "Browse in view," where view is the window's current view style. This appears to govern the view used when opening sub-folders from a window where the toolbar is visible, but a puny experimentation will betray that the setting is overridden by any "Always open in view" setting of a sub-folder. The discontinuance result is the same as it has ever been: an inscrutable system that users quickly give up any hope of understanding, resigning themselves to manually correcting view styles as needed during every interaction with the Finder.

    Mail

    Apple's venerable Mail application gets a significant facelift in Lion. Once derided as one of the ugliest bundled applications, it's now been transformed into the classiest. (It doesn't distress that the competition has stumbled a bit.) The screenshot below is dominated by the glossy Apple promotional e-mail for Lion in the right-hand pane, but explore past it at the surrounding interface.

    Mail in Lion: a class act Enlarge / Mail in Lion: a class act

    Or rather, explore at how much of the surrounding interface isn't there. With the exception of the toolbar, this window is completely about the content. There are no external borders, only the barest hint of internal borders, and, as befitting a suitable Lion application, no visible scrollbars. The toolbar and quick-access button bar ensue the monochromatic Lion style while quiet looking crisp. The cheeky red flag icon is furthermore a nice touch.

    After years of unsupported hacks to add a three-pane wide-screen view to Mail, Apple has finally taken the hint and made it official. There's also, naturally, a full-screen mode.

    At last, widescreen three-pane Mail for all Enlarge / At last, widescreen three-pane Mail for all

    Like the Finder, Mail's search territory supports Apple's snazzy fresh search tokens. These provide the fastest course to Do medium-complexity searches that I've ever seen in any e-mail application. It's too contaminated the search territory is so narrow and doesn't expand to fill utter available space in the toolbar, however.

    The main viewing pane shows entire threads by default, with each message appearing as a separate virtual piece of paper. Mail aggressively collapses quoted text within messages, displaying an adorable accordion consequence upon expansion.

    Mail plays an accordion animation when expanding quoted text Enlarge / Mail plays an accordion animation when expanding quoted text

    Keyboard support is excellent, allowing one-handed navigation for most common tasks. Expanding a thread and selecting a solitary message causes it to fill the right-hand pane, leaving behind the vanity that each message is actually a puny piece of paper.

    Mail has become more capable, as well. Simple wealthy text editing capabilities occupy finally been added. Mail is furthermore even better about automatically setting up accounts for common services. The account setup screens just inquire for a name, e-mail address, and password, and will usually Do everything else for you, including (optionally) correctly configuring and integrating calendar and chat services that might breathe associated with the e-mail account (e.g., Google Calendar and Talk).

    Rich text editing: let your font flag flyRich text editing: let your font flag fly

    If, dote me, you never seriously considered using any of the previous incarnations of Apple's Mail application, the version in Lion is definitely worth taking for a test drive—even if only as a random to experience an application that so thoroughly embraces the technology and aesthetic of the fresh operating system.

    Safari

    Besides adding support for another crop of fresh Web technologies (MathML, WOFF, CSS3 enhancements), the biggest change in Safari is its aforementioned consume of the fresh WebKit2 rendering engine, which moves webpage rendering into a separate, low-privilege process. (Previous versions of Safari already isolated plug-ins in separate processes.) This change is invisible to the user, but it should provide an additional layer of protection against browser-based exploits.

    Safari's downloads window has been subsumed into the toolbar and is now displayed as an iPad-style popover. (This is a standard control available to utter Cocoa applications in Lion.) When starting a download, an icon leaps from the point of the click into the downloads toolbar icon, which then displays a tiny progress bar. It's cute, informative for novices, and keeps the downloads window out of the way.

    Safari downloads in a popoverSafari downloads in a popover

    A little eyeglasses icon in the bookmarks bar triggers Apple's fresh Reading List feature, which saves the currently displayed webpage for later reading. This list of webpages is (or rather, will be) synchronized with Safari in iOS 5. Saved pages appear in the sidebar, accompanied by unattractively scaled favicons.

    Safari's Reading List:  redeem webpages to read later. (High-resolution favicons recommended.)Safari's Reading List: redeem webpages to read later. (High-resolution favicons recommended.)

    Reading List follows in the significantly dubious footsteps of other Apple products that occupy clearly been "inspired," let's say, by accepted third-party services. As was the case when Safari added rudimentary support for RSS, Reading List is unlikely to dislodge users who are already comfortable with their existing read-it-later service.

    But most people occupy never even heard of such a thing. Reading List's prominent placement in Safari will certainly spread awareness. This could translate into more customers for competing services, even as Reading List takes the lion's partake (sorry) of users.

    One last note on applications. The Finder, Mail, Safari, TextEdit, and even Terminal utter support full-screen mode and restore utter their windows when relaunched. Apple is definitely trying to lead by example.

    Grab bag

    As this review winds down, let's relax with a puny dip into the dilapidated grab bag, a grandiose tradition where the smaller features find their random to shine. As in years past, Apple has its own, much snazzier and more complete incarnation. Check it out if you want a broader overview of Lion's fresh features. These are just the ones that piqued my interest.

    System Preferences

    System Preferences occupy been shuffled, consolidated, and renamed in every major releases of Mac OS X. Lion doesn't disappoint.

    The preference formerly known as Appearance is now called General, and it includes a checkbox to globally disable application condition restoration. The Exposé & Spaces preference is now called Mission Control. Security becomes Security & Privacy. Accounts is now Users & Groups—a welcome change because, in my experience, most people don't know what an "account" is. Universal Access moves to the top row. And on and on. Dance, icons, dance!

    Your favorite system preferences: where are they today? Enlarge / Your favorite system preferences: where are they today?

    Individual preference icons can breathe manually hidden by the user thanks to the fresh "Customize…" menu item. (They will remain accessible from the View menu and via search.)

    Hide the preferences you're not interested in Enlarge / camouflage the preferences you're not interested in

    Click and hold on the "Show All" button to quickly jump from one preference to another via a drop-down menu. The View menu provided the same functionality in Snow Leopard, but the "Show All" button is closer to where the cursor is likely to be.

    Take a direct flight to your next preference paneTake a direct flight to your next preference pane

    Perhaps surprisingly, the MobileMe preference remains. It's joined by the new, awkwardly named Mail, Contacts & Calendars preference which manages, well, mail, contacts, and calendar accounts for a variety of online services.

    Centralized online service account management Centralized online service account management

    This includes the ever-popular "Other" service, which leads to a set of more generic configuration screens for other protocols and applications.

    Manual configuration and more esoteric account typesManual configuration and more esoteric account types

    The trackpad preference pane allows some, but not utter of the fresh gestures in Lion to breathe configured in limited ways. For example, the Mission Control signal must always breathe an upward swipe, but it can consume three or four fingers. utter of the gestures can breathe disabled.

    Limited choices for  signal configurationsLimited choices for signal configurations

    Finally, in case you needed any more evidence of Apple's newfound aversion to color in the Mac OS X interface, boost a explore at the fresh time zone selection screen.

    Your world,  utter silvery in the moonshineYour world, utter silvery in the moonshine Auto-correction

    Lion adds optional iOS-style auto-correction to the standard Mac OS X text control. It looks and works just dote the iOS incarnation from which it's so clearly derived. dote the other spelling and grammar checking options, auto-correction can breathe enabled on a per-document basis.

    I eagerly await the Compose Text Automatically optionI eagerly await the Compose Text Automatically option System-wide auto-correction: try to resist the  exhort to tap the screenSystem-wide auto-correction: try to resist the exhort to tap the screen Mobile Time Machine

    Time Machine isn't much back when you're on the road with your laptop. not a bit of Apple's portable Macs involve more than one internal drive, and making a Time Machine back up to another partition of the same drive benevolent of defeats the purpose.

    Lion includes a new, mostly invisible feature whereby Time Machine backups continue even when the backup volume is not mounted. This feature is only active for laptops, which is a shame (though you can enable it on desktops using the tmutil command-line tool).

    The implementation is strange. The mtmfs (Mobile Time Machine file system) daemon runs an NFS server on localhost which is then mounted at /Volumes/MobileBackups. In it, you'll find the customary Backups.backupdb directory structure that Time Machine creates for its backups. The actual copies of fresh and changed files—and only those files—are stored in /.MobileBackups by the mtmd daemon.

    This system provides some basic data protection for users on the go, beyond what's offered by applications that support Lion's autosave APIs. Mobile Time Machine, dote regular Time Machine, tracks utter file changes, not just those made by inescapable applications.

    There is some obvious overlap between Mobile Time Machine and the generational store used to support document versioning in Lion. Having two entirely separate storage locations and techniques for backup copies of files is suboptimal; perhaps the backends for these two features will merge in the future.

    Lock screen

    Lion's fresh lock screen has been restyled to match the login screen, with options to unlock or switch users, and it comes with the same subset of menu bar status icons visible in the top-right corner.

    Lion's  fresh lock screenLion's fresh lock screen Emoji

    Lion adds Emoji support to Mac OS X. So that happened.

    FACE WITH NO  advantageous  signal (U+1F645); MOON VIEWING CEREMONY (U+1F391); PILE OF POO (U+1F4A9)FACE WITH NO advantageous signal (U+1F645); MOON VIEWING CEREMONY (U+1F391); PILE OF POO (U+1F4A9) Terminal

    The Terminal application gets a few more graphical frills, sporting a fresh parameter for window blur, with separate settings for active and supine windows. The bundled Silver Aerogel theme demonstrates the effect.

    "I want to know what's behind my terminal window, but I don't want to know every detail.""I want to know what's behind my terminal window, but I don't want to know every detail."

    Terminal also—finally—supports 256 text colors with its fresh xterm-256color terminal type. Users of terminal-based text editors will surely approve.

    About This Mac

    The System Profiler application has been renamed System Information and now includes a comprehensive, effortless to understand overview of the entire system. The copious links to support documents, pertinent preferences, and channels for feedback are fantastic. This will breathe the fresh go-to location for anyone trying to remotely diagnose a Mac problem. As before, it's most easily accessed by going to the Apple menu and selecting About This Mac, then clicking the "More Info…" button.

    Don't worry, geeks, the dilapidated System Profiler interface with its much more circumstantial technical information is quiet accessible via the "System Report…" button. But it's likely that you'll rarely requisite the extra detail. boost a explore at what the fresh screens offer.

    Tech specs never looked so goodTech specs never looked so good Did you know that your  array has a manual?Did you know that your array has a manual? There  certain seems to  breathe a lot of "other"There certain seems to breathe a lot of "other" Unfilled RAM slots are sinful. I am ashamed.Unfilled RAM slots are sinful. I am ashamed. Five ways to  find supportFive ways to find support An excellent executive summary of warranty information and service optionsAn excellent executive summary of warranty information and service options Recommendations Want an eBook or PDF copy? support Ars and it's yours.

    Even at Ars Technica, a inescapable percentage of readers just want to know the bottom line about a fresh operating system. Is this a advantageous release? Is it worth the cost and the hassle of installing it? Excluding the first few dog-slow, feature-poor releases of Mac OS X, the retort to utter those questions has always been a resounding "yes." Lion continues this tradition, more than earning its $29 cost with a raft of fresh technologies and a substantially revised interface and suite of bundled applications.

    The standard caveats apply about software and hardware compatibility. Don't just flee out and upgrade your system as soon as you finish this review. Lion's digital distribution makes hasty upgrades even more likely. Patience! boost a few days—weeks, even—to research utter of your favorite applications and originate certain they utter flee fine on Lion. If you're quiet using some PowerPC applications, don't upgrade until you occupy replaced them with Intel-native alternatives. And before you upgrade, back up, back up, back up.

    All that you can't leave behind

    Though the Lion cognomen suggests the discontinuance of something, the content of the operating system itself clearly marks the start of a fresh journey. Seemingly emboldened by the success of iOS, Apple has taken a hatchet to decades of conventional wisdom about desktop operating systems.

    The same thing happened ten years ago in an even more theatrical vogue when Apple replaced classic Mac OS with Mac OS X. The fresh operating system changed the rules on the desktop, wedding composited graphics, smooth animation, and photorealistic artwork to a solid Unix foundation. Apple tried to leave utter vestiges of its dilapidated operating system behind—the platinum appearance, the Apple menu, even the desktop itself—but eventually bowed to some demands of long-time Mac users. Lion's changes will no doubt meet with similar resistance from experienced Mac users, but I suspect Apple will remain unmoved this time around.

    In the same course that Mac OS X so clearly showed the rest of the industry what user interfaces would explore dote in the years to come, Apple's own iOS has now done the same for its decade-old desktop operating system. iOS was less shocking to users because it appeared to gain from nothing, and the mobile operating system conventions it defied were ones that nobody liked anyway. The same is not suitable on the desktop, where users cling dote victims of Stockholm syndrome to mechanics that occupy distress them time and again.

    It may breathe many years before even half of the applications on a typical Mac behave according to the design principles introduced in Lion. The transition epoch could breathe ugly, especially compared to the effortless uniformity of iOS. In the meantime, let Apple's younger platform serve as a lighthouse in the storm. The Mac will always breathe more capable than its mobile brethren, but that doesn't breathe of value that simple tasks must furthermore breathe harder on the Mac. Imagine being able to stick a computer neophyte in front of an iMac with the same confidence that you might hand that neophyte an iPad today.

    The technical details of Apple's operating system that were once so needful that they practically defined its existence (e.g., recollection protection, preemptive multitasking) are now taken for granted. Mainstream reviews of software and hardware alike expend far less time pondering technical specifications and implementation details than they did only a few years ago.

    This phenomenon extends even to the geekiest among us, those who didn't just skip to the conclusion of this review but actually read the entire thing. Fellow geeks, inquire yourselves, Do you know the clock hasten of the CPU in the device you're reading this on? Do you know how much RAM it has? What about the recollection bus hasten and width? Now consider what your answers might occupy been ten years ago.

    Over the past decade, better technology has simply reduced the number of things that they requisite to dependence about. Lion is better technology. It marks the point where Mac OS X releases quit being defined by what's been added. From now on, Mac OS X should breathe judged by what's been removed.



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