Skip to main content

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

high sierra apfs file system fusion drives macos hands on review desktop
Image used with permission by copyright holder
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.

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.

Editors' Recommendations

Jon Martindale
Jon Martindale is the Evergreen Coordinator for Computing, overseeing a team of writers addressing all the latest how to…
Apple quietly backtracks on the MacBook Air’s biggest issue
The MacBook Air on a white table.

The new MacBook Air with M3 chip not only allows you to use it with two external displays, but it has also reportedly addressed a storage problem that plagued the previous M2 model. The laptop now finally has much faster storage performance since Apple has switched back to using two 128GB NAND modules instead of a single 256GB module on the SSD drive.

This was discovered by the YouTuber Max Tech, who tore down the entry-level model of the MacBook Air M3 with 8GB of RAM and 256GB of storage. In his tests, thanks to the two NAND modules, the M3 MacBook Air is nearly double faster than the M2 MacBook Air. Blackmagic Disk Speed tests show that the older M2 model with the problematic NAND chip had a 1584.3 Mb/s write speed, and the newer M3 model had 2108.9 Mb/s for the M3 model, for a 33% difference. In read speeds, it was 1576.4 Mb/s on the old model and 2880.2 Mb/s on the newer model.

Read more
The 6 best ways Macs work with your other Apple devices
A person holds an iPhone in front of a MacBook.

One of the best things about using more than one Apple device is the way they interact with each other. Apple has built all kinds of clever features into its famous ecosystem, and it means your devices all work together in a way that you just don’t get from any other manufacturer.

AirDrop might be the ultimate expression of this, though that's fairly well-known. Here, we’ve picked out six other great ways your Mac works with other Apple products. Most require you to have Bluetooth and Wi-Fi enabled, as well as for you to be using the same Apple ID on all your devices. Check the System Settings app on your devices to make sure the specific features are enabled, although most should be by default.

Read more
I never knew I needed this mini Mac app, but now I can’t live without it
Apple MacBook Pro 16 downward view showing keyboard and speaker.

Switching apps is something I do countless times every day on my Mac, so much so that I don’t ever think anything of it. That is until recently, when I discovered a new app that has me flipping windows in a new (and much-improved) way.

That app is called Quick Tab, and it’s designed to make app switching a little more painless. Now, I’ll admit that I’ve never thought of the traditional Command-Tab key combination as all that painful, but Quick Tab has swiftly shown me what I’ve been missing.

Read more