114 MACWORLD AUGUST 2019Mac 911
Solutions to your most vexing Mac problems.
BY GLENN FLEISHMANHELPDESK
Answering Your Questions and Sharing Your
Tips About Getting the Most From Your MacIMAGE: APPLECAN’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’sbest 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