Speculation was rife among users, rather than developers, that last June’s WWDC might have brought announcement of a major update to Time Machine coming in Catalina. Now that all Macs running Mojave have to boot from APFS, and with Catalina’s additional conjuring trick of a read-only APFS system volume, for many systems now the only drives still using HFS+ are those for Time Machine’s backups. So why hasn’t Apple fixed Time Machine so that it can back up to APFS yet?
Time Machine isn’t just popular because it’s bundled with macOS, but also because it integrates with so many features of macOS.
It uses hard links both for files and directories to create the impression that each backup is a complete copy of everything on a volume. It provides a familiar Finder-like interface to all your backups, which is also used by the Version Browser, which integrates with its backups too. Backups are indexed for Spotlight search, ensuring that Spotlight can see what’s in your backups and include them in searches. That metadata indexing is performed in the background once backing up has been completed, and doesn’t slow the backup process. Backups
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