(Actually, Time Machine will just warn you that it must first erase the destination drive, but the reason is because the drive has an incompatible format.) If you select the old Time Machine drive within the Time Machine app as a backup destination, you’ll be confronted with an option to erase all of the content on the selected drive and reformat it as HFS+. If you do accidentally convert a Time Machine drive to APFS, the Time Machine app will no longer recognize the drive as a backup drive. Resist the temptation to go all APFS Time Machine will not cooperate with you. Luckily, installing macOS High Sierra won’t automatically convert Time Machine drives to APFS, but it’s possible to change the drive’s format to APFS from within Disk Utility or via the Terminal app. When you convert an HFS+ formatted volume to APFS, any hard links found during the conversion process are automatically changed to symbolic links, thus breaking your Time Machine backup into a collection of almost useless files. (Time Machine in its current incarnation is unable to use an APFS formatted volume for backups.)ĪPFS, on the other hand, does not support hard links. Hard links are just one of three types of file linking that HFS+ supports, the others being symbolic links and aliases. Time Machine uses the magic of hard links, a feature that HFS+ file systems have to catalog and keep track of which files in a backup make up the current version of an app, document, or directory. Time Machine drives must be formatted in HFS+. However, there are some very important caveats that Time Machine users should be aware of. In its current incarnation, the Time Machine app is mostly compatible with APFS that is, you can back up an APFS formatted drive using Time Machine, as well as restore files from a Time Machine backup to an APFS formatted drive. It’s a good idea to check any file system utility you may be using for APFS compatibility. We’re going to primarily look at these three Apple-provided apps and services, but third-party apps may also be affected by the change to APFS.
Related articles: Translating Apple’s New High Sierra & APFS Compatibility Document, How to Revert a drive from APFS back to HFS+
And like any big deal, there’s a lot to understand about how APFS will work with existing Mac apps and services, including Time Machine, Boot Camp, and File Vault.
That makes the new APFS file system a big deal. While there have been some minor upgrades to HFS+ over the years, the Mac’s file system has stayed pretty much the same since 1998.
The Hierarchical File System (HFS) followed in September 1985, and the last file system upgrade was Hierarchical File System Plus (HFS+), which was released with Mac OS 8.1 in January 1998.ĪPFS and Time Machine, Boot Camp, and File Vault It was designed to meet the demanding needs of a 400 KB floppy disk.
Macintosh File System (MFS) was the original file system introduced along with the Macintosh in January 1984. Apple has only changed the default Mac file system twice in its 33-year history. Changing the primary file system used by the Mac, or for that matter, any computer system is a big deal. MacOS High Sierra contains many new features and capabilities, but APFS (Apple File System) is certainly one of the biggest changes.