What is apfsd?

2017-10-09 17:00

apfsd is the daemon for APFS, the Apple File System. It runs on every modern Mac.

What is APFS?

APFS replaced the older HFS+ as the standard file system starting with macOS High Sierra in 2017. It was built for modern storage, especially SSDs.

What does apfsd manage?

Space sharing: several volumes can share the same pool of free space on a disk, instead of each having a fixed size
Snapshots: frozen copies of the file system at a point in time, used by Time Machine and macOS updates
Clones: instant copies of files that share storage until one copy is changed
Encryption: built-in support for full-disk and multi-key encryption
Crash protection: designed to stop data loss if your Mac loses power without warning

Is it always running?

Yes. It manages APFS containers and volumes, handles snapshot creation and removal, and works with other storage processes. Time Machine, in particular, causes regular apfsd activity because it creates snapshots.

Does it use many resources?

Normally very little. It may do more during:

Time Machine backups
macOS updates (which use snapshots so you can roll back)
Large file operations that involve clones or snapshots

Should you worry?

No. If your Mac uses APFS (and it almost certainly does), apfsd is essential.

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