I won’t say it’s the worst, but from testing a Sys24, macOS 10.14 on APFS external SSD hanging off my venerable iMac from 2009, purchase retrospectively to have a machine that was able to boot 10.6.3 it’s probably the first to slam the took shut AND MAKE USELESS any Mac that WAS able to boot into 10.6.3+ or 10.6.5+. I now havem from the future (it’s 2021 in this comment) some grasp of the consequences of this 7th, or is it eighth total rehash since my Mac 128. Here is the rest of the technical note verbatim, with our translation of Apple’s writing in italics: Those Macs that use Fusion Drives (like the iMac, for example) or good old hard disk drives will not be converted, period. So basically, if you install APFS on any Mac that uses a solid-state drive as a built-in boot drive, it will automatically convert to APFS and you will not have a choice. You can’t opt out of the transition to APFS. (Rocket Yard emphasis) Fusion Drives and hard disk drives (HDDs) aren’t converted.

When you install macOS High Sierra on the built-in solid-state drive (SSD) of a Mac, that drive is automatically converted to APFS. APFS features strong encryption, space sharing, snapshots, fast directory sizing, and improved file system fundamentals. Probably the most important information from Apple is this quote:Īpple File System (APFS) is the default file system in macOS High Sierra for Mac computers with all-flash storage. Thanks to sharp-eyed Rocket Yard commenter Chris pointing us to an Apple support document, we now have a bit more information on macOS High Sierra, Apple File System, and how it all works on Macs and on volumes that are formatted with the legacy HFS+ file system.Ĭhris pointed us to this Apple tech document, titled Prepare for APFS in macOS High Sierra.

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