August 2019 • Macworld 119HELP DESKCan’t select a drive to use with Time
Machine? It might need reformatting
If you use Time Machine, you know that macOS
asks you whenever you mount a new external drive
whether or not you want to use it as another Time
Machine destination. One of the backup service’s
best features is that it can create archives on
multiple volumes at once, and remembers backup
volumes when they’re removed, so you can rotate
through disks and keep one or more offsite.
However, you might mount a drive and want to
use it with Time Machine and be unable to select it.
That’s typically because the volume isn’t formatted
using the old standby, HFS+, labelled ‘Mac OS
Extended (Journaled)’ in Disk Utility.
Time Machine can only create backup archives
on HFS+ volumes because of some of the
peculiar properties of how it creates snapshots by