First released 16 years ago, it was destined for Time Capsules, and relied on hard links in HFS+. It soon used APFS snapshots, and now uses them as the basis for its backups.
HFS+
Disk errors threaten your data: how to detect them, how to use First Aid in Disk Utility, how to use fsck, and what to do with the disk afterward.
Where to look for file metadata in the Finder, and how you can customise it, in spite of its apparent confusion. And how APFS takes care of extended attributes for you.
How does copy on write work, and how do clones grow apart? What effect do they have on the use of space and performance?
When you updated your iPhone or iPad to iOS 10.3 six years ago, you were among the first to use Apple File System, although you didn’t know it at the time.
Plain read/write (UDRW), sparse image (UDSP), and sparse bundle (UDSB) compared for storage efficiency, performance, and convenience.
In Monterey and Ventura, regular read-write UDRW disk images can now be APFS sparse files, and work more efficiently than sparse images or sparse bundles.
How APFS containers and volumes work. What hard links, clones and sparse files are, and when they break down.
You’re in control of a traditional file system, but with snapshots, clones, sparse files and other volumes sharing free space, APFS isn’t as simple.
When Time Machine makes its backups to APFS storage, just what can and can’t you do? How can you prevent large temporary files from stealing space on storage?
The Eclectic Light Company 