Boot disk volume layout is intricate in Big Sur. M1 Macs lose the EFI partition on their internal SSDs and gain two more for APFS. Contents of /System/Volumes has also changed.
Volume layouts are fairly straightforward until you have two or more bootable systems with Volume Groups. Details and advice for those with macOS 10.15 or 11.
Adds a new log view of background task scheduling and dispatch, greatly improves volume info, and fixes a rare crash.
Disk structure diagrammed for comparison, from the partition table, to HFS+ and APFS volumes, with further references.
What you need to know about the APFS file system, its containers and volumes, so you can understand errors and how to repair them.
What you need to know about the HFS+ file system, so you can understand error reports and how to repair it using Disk Utility and other tools.
Apple says that if you run First Aid on a disk, each of its volumes is checked too. Is that really true?
One new tool to list capacities on mounted volumes, the other to deliver detailed information on keychains.
If something goes wrong with Catalina’s boot Volume Group, it seems there’s no way to repair it, or change the Data volume. Or is there?
APFS adds 6 volume roles, including one which supports Time Machine backups. And per-file encryption is coming.