7 things to know before upgrading to MacOS High Sierra 10.13

The latest version of MacOS changes some of the operating system's underlying plumbing, but it's more evolutionary than revolutionary by design.

Lori Grunin Senior Editor / Advice
I've been reviewing hardware and software, devising testing methodology and handed out buying advice for what seems like forever; I'm currently absorbed by computers and gaming hardware, but previously spent many years concentrating on cameras. I've also volunteered with a cat rescue for over 15 years doing adoptions, designing marketing materials, managing volunteers and, of course, photographing cats.
Expertise Photography, PCs and laptops, gaming and gaming accessories
Lori Grunin
8 min read

Photos in High Sierra now has all the adjustment tools easily accessible on the side panel.

Lori Grunin/CNET

Now that they're free, operating system updates are often just as much about fixing the underlying plumbing of a device as they are about adding new and notable features. That's largely the case with MacOS 10.13, otherwise known as High Sierra. 

For the most part, don't expect jaw-dropping changes or totally new interfaces. Instead, you get new features such as Safari's autoplay blocking, the ability to edit iPhone's Live Photos in Photos, and really fast file copying on SSDs. On the other hand, that means no sea-changes to your existing workflows, and some nice quality-of-experience enhancements if you're a big user of those applications.

Performance is virtually identical, at least on an up-to-date MacBook Pro (13-inch). File moves are instantaneous under both High Sierra and Sierra, but copies of large files (like a 4.3GB ISO image) are instantaneous on AFS, the updating disk file system that's now default for anyone who doesn't have a Fusion drive or an old spinning hard drive. That's really important if you work with video and other massive-file generating tools.

Battery life seems to be slightly better -- we got about 30 minutes more. But it also turns out that High Sierra breaks one of our benchmarks. Oopsie. 

Just hours before the High Sierra update become available for download, ZDNet reported a Keychain security vulnerability in MacOS. In response, Apple said the following: "MacOS is designed to be secure by default, and Gatekeeper warns users against installing unsigned apps, like the one shown in this proof of concept, and prevents them from launching the app without explicit approval. We encourage users to download software only from trusted sources like the Mac App Store, and to pay careful attention to security dialogs that MacOS presents."

Apple did not provide a timeline for a possible fix. However, because the vulnerability is said to affect High Sierra and previous versions of MacOS, waiting to update won't make you any safer.

Should I update? TL;DR

Yes, if you answer any of these affirmatively:

  • You're paranoid about security. Some say that the update is essential in order to get a complete set of security fixes, but it's not like Apple is going to keep Sierra unpatched. Enterprises are running even older versions and they'll continue to be patched. But if you think the potential security advantages outweigh the possibility of running into application issues, then update. 
  • Your system has an SSD, not a Fusion Drive or HDD
  • You've updated your iPhone or iPad to iOS 11 and shoot photos and videos with the new file formats
  • You're a big Photos user
  • You have a complicated family to manage with iCloud
  • You've been screaming for the specific capabilities added in those particular applications

Updating will also get you the latest security fixes (the Keychain exploit above notwithstanding). That said, my standard recommendation is to wait at least a month before updating and let the early birds find the most glaring problems and glitches, which are generally handled by followup point upgrades.

Want a more detailed look at what you need to know about High Sierra? Read on.

MacOS High Sierra has some really cool new features

See all photos

It's a free upgrade that works on 2010 and later Macs  

High Sierra has the same requirements as Sierra, so if you're running that now the answer's yes. If you never updated to Sierra, check out Apple's compatibility list. (If your Mac was built in the last seven or eight years, you should be good to go.)

It flips the switch on overdue architectural changes

There's a lot going on under the hood to lay the groundwork for future enhancements, though much of their benefit doesn't appear at the moment. When it comes down to it, many of them Apple really couldn't put off.

  • In order to be able to work with iOS 11's new file encodings -- the HEIF (photos) and HEVC/H.265 (video) which allow for better compression to save space on your iPhone -- Apple had to update MacOS to understand them.
  • The successor to the ancient HFS+ file system, Apple File System (AFS), was rolled out last year, but with High Sierra became the default. At the very least, AFS' 64-bit addressing is essential to the upcoming iMac Pro for many reasons, not the least of which is the ability to support that system's configuration with a 4TB SSD and higher. Plus, SSDs have different failure characteristics than hard disk drives -- one bad bit and buh-bye -- so the file system needs different types of redundancies and checks for reliability.
  • And the company's Metal graphics programming interface really needed the Metal 2 update for several reasons, such as helping Apple overcome its reputation as a VR no-show and creating an efficient way to develop for both iOS and MacOS. To compete with Windows-based gaming laptops and mobile workstations, most which don't concern themselves with the thinness to the extent Apple prizes, the company had to add the ability to connect to an external GPU; we won't even see those until mid-2018. Most notably, though, without Metal 2 those pricey iMac Pros would be all dressed up with 18 CPU cores and Radeon Vega GPU but have nowhere to go.

AFS is a big win -- for SSD owners 

In addition to the aforementioned reasons AFS is necessary, it also theoretically improves performance and security. That's always a nice perk. But despite having over a year to work out the kinks with AFS, Apple rolled out High Sierra with a big caveat: AFS will only work with SSDs for now. You shouldn't use it for HDD+SSD Fusion drives and regular HDDs (spinning hard disks). Don't even think about it. When High Sierra went final, beta testers who had converted non-SSDs to AFS were greeted with a mind-bending list of instructions for banishing AFS from their systems.

HDD-supporting AFS is definitely coming, but we don't know when. But it means the systems which need the performance boost the most don't get it yet. It also means you can't use it on most drives used for backup, so no performance boost there.

On the other hand, if you do have a system with an SSD, AFS delivers noticeably better speed, at least for same-disk file copies for GB-size files, and security that's probably worth the update now rather than later.

Check your essential apps for compatibility before updating

Architectural changes like a new file system or changes to permissions -- yup, there are changes to SKEL (Secure Kernel Extension Loading) aka Gatekeeper -- may make it difficult or impossible to install some applications in the beginning. Luckily, this workaround seems to still work. So make sure your most prized third-party applications will install before you commit. (Your currently installed ones should remain installed.) For instance, I use VMWare Fusion to run Windows and that won't be fully compatible until October.

Use iOS 11? Update for Photos. Or not

As I mentioned earlier, if you plan to take advantage of the extra space savings offered by the new photo and video file formats, you'll have to update to MacOS to be able to view or edit them on your Mac. You don't have to, though; if you prefer to keep it compatible, just go into Settings/Camera/Formats on your iPhone and change it from "High Efficiency" to "Most Compatible."

If you're a big Photos user, Apple has certainly improved the organization and editing interfaces to make using the software more streamlined, and added the same Loop, Bounce and Long Exposure effects for Live Photos that you've got on iOS 11. (Unfortunately, on the bigger-than-phone-size screen of a computer, it's easier to see how the effects degrade the quality.)

And now Photos has an extensions interface where other companies can serve up projects for creating books, cards, calendars and so on. All stuff you could do before, but now from within Photos. And it will happily tell you that the book you just laid out will cost $120.

Want Safari 11? You don't need High Sierra

The latest version of Safari has some really nice features, implemented in a way I wish other browsers would -- you can set default zoom levels on a per-site basis and quickly get to those per-site settings right from the main menu, for example, and the Intelligent Tracking Prevention (which expires third-party cookies used to track you across the web after 24 hours) is an easy way to take a basic step toward more privacy.

And of course there's the ability to block autoplay videos as long as they make noise. Apple claims it's also faster, and it might be when measured in milliseconds, but in practice I really don't notice much of a difference bouncing back between that and Chrome.

But those don't require an OS update. Updates to Safari and iTunes hit the Mac earlier this month as separate downloads. On the other hand, some capabilities of Safari 11 do require High Sierra, however, most notably accelerated streaming HEVC video playback. But there isn't a lot of that content available yet to stream.

There are a smattering of other changes

If you don't already use one of the myriad services available for collaborative editing -- Google Drive, Dropbox, Box, Microsoft OneDrive and so on -- Apple now offers basic file sharing with real-time updates. It also enables the "universal clipboard," which is essentially the same thing but across nearby devices you've got logged into the same account (sort of like Airdrop), but it's hard to tell what's new. And it makes it easier to manage your family plan.

But the rest could have easily been slipstreamed into Sierra without fanfare. Do you use the Touch Bar? Apple has made some "enhancements" to its operation. I put "enhancements" in quotation marks because some of them don't really feel like it. For instance, you can now flick the brightness and volume controls instead of sliding them. But flicking properly doesn't feel a lot faster or easier than just pressing and sliding. The expanded color picker options look pretty, but to use them you have to constantly look away from the screen.

Top Hits in Mail search results? Meh. Split screen message editing in full screen? Sure. A more compact message store? Hell yeah, at least for the few, the proud, the Apple Mail users. FaceTime Live Photos (to capture something on the other end of the call)? More of an iOS perk. The ability to pin Notes and use tables? Big news for Notes users.

For more details, here's a breakdown of the different application updates.

Editors' note, 7:24 p.m. PT: This story has been updated several times since its original publication at 10 a.m. PT to incorporate news of a MacOS security issue, Apple's response and the resulting download recommendations.