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By Jason Snell

macOS High Sierra: A mostly under-the-hood update

Note: This story has not been updated for several years.

If you were a Mac user eight years ago you may remember Snow Leopard. It was the follow-up release to Mac OS X Leopard, and as Apple explained at the time, the focus was on under-the-hood improvements that would lead to a better, brighter future for the Mac, but be largely invisible to the upgrading user.

In the end, Snow Leopard did offer a bunch of user-interface changes (if you knew where to look), but it was definitely more about laying a new foundation. Apple has tried this same technique with other half-step updates in the past few years—Mountain Lion followed Lion and El Capitan followed Yosemite. But today’s release of macOS 10.13 High Sierra is the most Snow Leopardy of any macOS release in the last eight years. (Snow Leopards do not actually live in the high Sierras, for the record.)

High Sierra is truly a follow-on release to Sierra that offers a bunch of under-the-hood changes that will impact the Mac experience for developers today and for users in a while. But in terms of major new features that will transform your everyday Mac experience, there just isn’t much.

In fact, the biggest user change in High Sierra is probably Photos, which gets some major interface changes and file-compatibility features. By default, Apple’s most recent iOS devices begin taking pictures and videos in entirely new file formats when they’re updated to iOS 11—and if you want full compatibility with Photos and iCloud Photo Library, you’ll either need to update your Mac to High Sierra or change a setting on all your iOS 11 devices in order to force the devices to revert to the old file formats.

A new filesystem for some

The single biggest change in High Sierra is implementation of the new Apple File System (APFS). With this release, all Macs with flash-only internal storage will have those drives upgraded to Apple’s new filesystem format. (Users of spinning discs and Fusion Drives will remain on HFS+.)

In the long run APFS has huge potential to make the Mac better. Partition management is much easier in APFS, and disk partitions can share space, so you don’t have to lock your partitions into specific sizes. Snapshot and revision features have the potential to make Time Machine (and other backup software) far more efficient someday. APFS makes duplicating files in the Finder nearly instantaneous… by pointing at the existing copy of the file data on disk until you modify it, at which point the new file is written to disk.

Most important, perhaps, is that APFS is a filesystem written for an era of flash-storage devices, rather than spinning disks. APFS is much smarter (and faster) at flash storage than HFS+ could be.

But changing the filesystem has ramifications for compatibility. If you make a backup utility you may find that APFS is undocumented and choose to tread lightly and with great care.

If you have a flash-only Mac, upgrading to High Sierra means you’ll get APFS. It’s a big leap. I have a hard time believing Apple would make the leap if it weren’t confident about its implementation—and APFS has been powering iOS devices for many months now—but if you rely on disk-cloning utilities or do other funny things with your disk, maybe it’s worth letting others dip their toes in first.

Other changes under the hood

High Sierra features Metal 2, which is the latest version of Apple’s graphics framework. Apple says that this will lead the Mac to be that much more of a graphics powerhouse for games and other purposes, which is great. This feels more relevant for the next generation of Mac hardware, or perhaps for this year’s crop, than for older systems.

Similarly, High Sierra adds support for VR headsets and development tools. The Mac has been behind in this area for quite a while, and it’s good to see that Apple’s finally trying to lay a foundation for VR development on the Mac. Again, though, this will require the latest and greatest hardware—the most recent iMacs, and the forthcoming iMac Pro and Mac Pro.

High Sierra rolls in support for Swift 4, the latest version of Apple’s new programming language and compiler. It’s a good sign that Swift development is progressing, but this is similarly not a feature that most users will notice or care about—though they may reap the results of more apps written in Swift, eventually.

Changes to Safari

High Sierra includes Safari 11, the latest version of Apple’s built-in web browser. As is standard, the latest Safari is also available for the two previous versions of macOS, El Capitan and Sierra. So while this is a feature that rolls out with High Sierra, it also doesn’t require the upgrade to the new version.

Safari 11 features more tracking protections, in order to thwart trackers that try to build a personal profile of you and then follow you around the web. Pages that automatically play video are now prevented from doing that by default; if there’s a site you’d like to autoplay video from, you can add it in Safari’s Settings. And if you’re a fan of Safari Reader, which simplifies webpages to their base text to make them more readable, you can set Reader to turn on automatically on all stories, or on stories for specific websites.

There are a bunch of changes to WebKit, the open-source web platform that powers Safari, as well. A lot of these changes will improve Safari compatibility with complex web apps, but for you to see the benefits, the developers of those web apps will need time to check the new Safari out and support it.

Among the new features in WebKit is support for the multimedia features known as WebRTC, which have been supported by Firefox and Chrome for some time now. These features can let browsers act as full real-time multimedia communicators (think Skype and Google Hangouts) without any plug-ins.

Unfortunately, what I’ve heard from some developers is that the shipping version of WebRTC on macOS High Sierra and iOS 11 is buggy, which means that they can’t yet support Safari in their apps. There are specifically issues with managing and maintaining consistent audio inputs. Also, despite mentioning the Opus audio codec early on, Apple’s support may be missing—one developers I talked to suggested that he can’t find any support for the Opus codec for playback, which would be a dealbreaker.

Other visible improvements

Beyond the changes in Safari and Photos, you’ll find a few other apps with refreshed features in High Sierra. Mail search has been improved, and Mail now uses a compressed format for storing messages, which results in a disk-space savings.

Siri’s been updated with new Apple Music integration called Personal DJ, which lets you issue commands like “play some Alternative next.” Unfortunately, there’s still no sign that Siri on the Mac will ever be able to connect to anything on the Mac beyond the basics introduced last year. There’s no integration with Automator or scripting of any kind. It’s a missed opportunity.

Spotlight gets a new flight-status feature, so you can type an airline flight code and get a flight tracker right within the Siri window. Notes has been updated for iOS 11 compatibility, so you can see handwritten and scanned items, as well as support for tables.

In many ways, the most important macOS feature these days is compatibility with the latest iOS release. Macs running High Sierra support new iCloud features, such as family iCloud space sharing and the ability to share files saved on iCloud Drive with others.

There are also a few minor updates to the Touch Bar in High Sierra, including an easier way to adjust brightness and volume with a single gesture from Control Strip. But it’s a bit disappointing that there aren’t more changes to the Touch Bar, which has been out for a year now. Third-party utilities still have no access to Control Strip, which would have the potential to make the Touch Bar more useful across apps.

So should you update?

As impressed as I was with all the updates in iOS 11, I’m lukewarm about High Sierra. There’s nothing wrong with it, but it’s definitely in the spirit of Snow Leopard. The update is something Apple needs to do in order to lay technical groundwork for the future, but technical groundwork is not a motivator for users to update their systems and risk incompatibilities.

Let’s be realistic: In the end, you will need to update to High Sierra, because it will provide you with the latest security updates and features that your apps will demand. But in the short term, until developers better come to grips with the new filesystem and we’ve waited to see if there are bugs or security flaws that could bite this release, I think it’s wise for most users to keep their finger off the upgrade button for High Sierra.

The time will come when you need to ascend to High Sierra. But you may want to wait at the base camp for a few weeks or months until hardier souls tell you it’s okay to make the journey.

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