November 10, 2020 update: given Apple’s usual support practices, the security patch released in September 2020 for macOS 10.13.x was likely the final one they will make available. Systems incapable of running macOS 10.14.x or later—now at least five years old and generally more than eight years old— should be considered for retirement.
November 29, 2017 update: for users who installed macOS High Sierra 10.13.1, please install an important security update to address a root access vulnerability as soon as possible.
Original announcement: On Monday, September 25, 2017, Apple released version 10.13 of the Macintosh operating system, High Sierra. High Sierra is compatible with any Macintosh that can run Sierra (macOS 10.12). As with previous iterations of the Macintosh OS, it is a no-charge upgrade to any compatible Mac.
On the surface, Sierra is even more of an incremental improvement to macOS 10.12 Sierra than Sierra was to macOS 10.11 El Capitan. The user interface of the OS remains mostly untouched. However, several significant technical changes deserve mention.
From HFS+ to APFS
The largest and most significant change in High Sierra is the move from the aging HFS+ (Hierarchical File System Plus) file system first introduced in 1998 to the newer APFS (Apple File System) file system. APFS has already seen significant use in iOS 10.3 devices, but this is the first time that the new file system is being implemented on a large scale for macOS devices.
APFS has some significant improvements to the HFS+ file system, including but not limited to support for encryption at both the file and the volume level, being optimized specifically for SSDs, the ability to address far more files on a single drive, and much faster duplication of data.
On installation, High Sierra will only automatically convert SSD or flash drives to APFS. It will also only convert the boot partition and leave any other partitions unchanged. Conversion to APFS for magnetic drives can be done after the fact with Disk Utility, though there is not yet much data on how well APFS works on traditional hard drives. Of particular note is that despite working in the developer betas, APFS is NOT supported on Fusion Drives for the release version of High Sierra. Even those that are currently running the High Sierra Beta on an APFS Fusion Drive will need to reformat it with HFS+ to run the release version.
As with every major operating system upgrade, it is always a good idea to back up one's data first, but this is doubly important with the move to a new file system. During the conversion, the OS does its best to make minimal changes to existing user data, but precautions should be taken nonetheless.
Under-the-hood graphics changes
High Sierra also adds some additional graphics-related features. Several are GPU-related; the graphics API is updated to Metal 2, with some specific features to support VR. The operating system also does window-drawing operations using Metal 2, which Apple claims will speed up Finder performance (in testing, we didn't notice much difference).
Similarly, High Sierra supports HEVC and HEIF, new video and image formats respectively, that are designed to store high-resolution files at a much smaller disk footprint than before.
Bundled application updates
Several of the macOS bundled applications are getting updates with High Sierra, with Photos the most significantly changed. It features a more streamlined sidebar and adds a new Imports menu that allows users to view and sort their photos by the date and time they imported them. The interface for editing photos is also more detailed, and the app keeps track of whether or not a photo has been edited and marks them accordingly for searching. Photos also adds support for third-party extensions.
Safari gets an update to version 11. It adds some new privacy features that prevent advertisers from tracking users and has better ability to prevent unwanted cookies from being saved to the browser. It also adds a button for effectively removing ads from the page by stripping out all special formatting. It also allows you to granularly remember browser permissions for individual sites (such as running content) and keeps them from session to session. It also prevents videos from auto-playing on websites without user permission.
Compatibility at Penn
ISC and others across the University have tested macOS High Sierra extensively and has found that many commonly used products and software function as expected, including:
- Adium
- Chrome .current
- dataComet-Secure
- Fetch
- FileMaker Pro/Advanced 15.x and 16.x
- Firefox .current
- Firefox 52esr
- Microsoft Office 2016
However, there is one notable exception:
Adobe Illustrator versions CC 2017 and prior are known to have issues with High Sierra and can crash systems with it installed. The High Sierra 10.13.4 update resolved this issue.