High Sierra's Apple File System will not support Fusion Drives at launch

By Jon Martindale Published September 20, 2017

If your Mac system has one of Apple’s Fusion caching drives, then you may need to take some extra steps when upgrading to the new version of MacOS — High Sierra. The new Apple File System (APFS) will only support flash-based storage devices at launch, so if your drive, Fusion or no, is currently using APFS, you will need to convert it back.

The High Sierra update for MacOS didn’t blow us away when we first got out hands on it, but it will bring a number of changes to the operating system when it launches on Monday, September 25. One of those is a move toward a more modern file system, APFS. It adds a number of new features, including native support for encryption, support for snapshots and clones, optimizations for solid-state storage and support for many more individual files and folders.

Recommended Videos

However, while beta versions of the High Sierra update did help convert Fusion drives to the new standard, the actual launch release won’t support traditional hard drives or Fusion Drives.

If you haven’t used the High Sierra beta, or didn’t convert your Fusion Drive or hard drive to the APFS file system, you have nothing to worry about. However, if you did, you need to follow Apple’s instructions on how to downgrade your system back to the HPS+ format, according to Ars Technica.

It’s a somewhat lengthy process that involves backing up your data, removing all data on your storage drive and then reinstalling MacOS with the latest version using the legacy HPS+ file system, so make sure you’re well prepared before starting. Don’t be put off though, Apple’s guide is clear and has easy-to-follow instructions at each step of the process.

Since it’s not clear if or when Apple will make the APFS file system compatible with more traditional storage mediums like the Fusion Drives, it’s probably a worthwhile endeavor to update your system to the new operating system version, even if it doesn’t add much for most users. It will help futureproof your system in a number of behind-the-scenes ways and it’s always possible that you will be able to upgrade to the new file system in the future.

Evergreen writer

Jon Martindale is a freelance evergreen writer and occasional section coordinator, covering how to guides, best-of lists, and…

Topics

Computing

I’m using this powerful macOS feature that many ignore, and you should too

Background apps on M4 MacBook Air.

MacOS is preferred for its fluidity and seamlessness. Of course, solid hardware and fire-breathing silicon add to its appeal, but the software experience developed by Apple focuses on convenience and security more than anything.

In its quest to do so, however, Apple has often ignored glaring functional holes in the OS. The lack of a native clipboard is one such as miss, one that is addressed by excellent third-party apps such as Maccy. The Menu Bar is another similar tale of missed opportunities.

Computing

Apple needs to fix the basics for macOS 26, or let AI run the show

Background apps on M4 MacBook Air.

The Mac apps community is a wonderful place to find utilities that can supercharge your computing experience. Alfred, Raycast, AlDente, and Rectangle are some of the most highly recommended apps for macOS users these days. The open-source community has also produced a few utilities (and their forks) that I use on a daily basis.

If you read between the lines, you'll notice that these apps fill a functional gap that Apple has yet to offer natively. On the other side of the computing ecosystem, Windows has served those perks for years. Will the next big software upgrade, macOS 26, finally give users an in-house fix? We’ll only get the answer at WWDC 2025 in just over a week from now.

Computing

How to keep your Apple devices safe from AirPlay attacks

Apple AirPlay streaming to another device.

Apple’s approach to building new features has always been rooted in safety and seamless convenience. Take, for example, AirPlay, a wireless standard created by the company that allows users to stream audio and video from one device to another.

AirPlay works not just across Apple devices, but also on TVs and speakers cleared by the company to offer the wireless streaming facility. That also makes it a ripe target for attacks, and it seems there are, in fact, vulnerabilities in the wireless lanes that could allow bad actors to seed malware and infect more connected devices.