What format for hard drive to use as time machine backup
Hard drive format criteria for time machine use
iMac 21.5″, macOS 11.5
Hello, shermm.
This from the support document –
Types of disks you can use with Time Machine on Mac - Apple Support:
https://support.apple.com/guide/mac-help/types-of-disks-you-can-use-with-time-machine-mh15139/mac
"APFS or APFS Encrypted disks are the preferred format for a Time Machine backup disk. If you select a new backup disk that’s not already formatted as an APFS disk, you get the option to erase and reformat it. If the disk is a Mac OS Extended format disk that contains an existing Time Machine backup, you aren’t asked to erase and reformat the disk."