MacOS High Sierra just came out of beta and is available to the public, but some users may feel left out by the current limitations of Apple's new file system (APFS). The new system currently supports machines with all-flash built-in storage, so those with Fusion Drives can't use it. However, a report from MacRumors cites an e-mail to a reader from Apple's Craig Federighi that states APFS will support Fusion Drives with later software updates. Apple confirmed to Ars that this is the case: support for Fusion systems will come in future updates.

Those who tested the beta version of High Sierra were in a pickle before the official release of the update on September 25. Because APFS did not support Fusion Drive systems like older iMacs and Mac Minis at launch, those who had their file systems already converted to APFS needed to revert them back to the older HFS+ format. APFS support was included in early betas of High Sierra but was then removed in the most recent beta versions.

Apple provided a long list of instructions on how to change back to the HFS+ format before High Sierra became available. Only those who downloaded beta versions of High Sierra had to worry about converting back before the official version was released. Now, with High Sierra available to all, those with Fusion Drives simply will not be updated to APFS until support for the new file system is released in later updates.

APFS replaces the old-school HFS+ format that Apple has used for years. In macOS High Sierra, it updates systems with a more modern file system that includes support for solid-state drive optimization, built-in encryption, and general performance improvements.