Confused by this on APFS? So you should be, as it’s complicated by features like snapshots, sparse files, and the file system itself. There’s no single figure.
snapshot
Tired of HFS+? Disenchanted by APFS? Why not copy or back up to a different file system? Here are crocodiles waiting to bite you.
How to repair a snapshot with an error when it’s one of your backups on a hard disk? Currently this seems impossible, putting all those backups at risk.
Explains the identifiers, sizes and tidemark data shown for snapshots in Disk Utility, in Monterey.
New for Monterey: Disk Utility now offers complete features for the management and maintenance of snapshots.
How to recover a deleted app or document without having to restore from your Time Machine backup. Simple steps and no use of Terminal.
A great advance in APFS which enables Big Sur’s Sealed System Volume, and backups being made to APFS. Here they’re fully explained.
A lot of what Time Machine does when making backups to an APFS volume remains a mystery. So far we don’t understand the magic used by Apple.
Snapshots are designed to make it easy to roll back to a previous state. Why then can’t you use a snapshot to roll back to an earlier version of Big Sur?
It’s common to want or have to change either the source or destination disk for backups. How well does Time Machine to APFS cope with that?
The Eclectic Light Company 