When you try ejecting a single volume of a bootable volume group on an external disk, other volumes are also ejected even though you chose to keep them mounted.
Disk Utility
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.
Don’t waste time trying to discover which files are still open when you want to check or repair an APFS disk and Disk Utility throws an error. Here’s the solution.
When your backups are stored on hard disks, even though they may use APFS, it’s important to check they’re sound. How to do better than Disk Utility.
A major new version of macOS bringing few big changes, but lots of opportunity for improvements and fixes.
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.
The differences between HFS+ and APFS volumes explored. What a container is, and how to add new HFS+ and APFS volumes to a disk.
Why deleting either the System or Data volume, but not the whole Volume Group, could get your Mac into trouble in macOS 11 or 12.
Finder refuses to eject a volume because it’s in use, or Disk Utility complains that it can’t unmount a volume. Here’s what to do about it.
The Eclectic Light Company 