January 2022 • Macworld 93or Thunderbolt cable is in the midst
of failing, particularly if your drive
unmounts randomly at other times.
Swap in another cable to see if the
behaviour goes away.)
This is typically an issue
only with a Mac laptop, and
not a desktop, as laptops
are designed to reduce wear
and tear on the battery, even
when they’re plugged into
power. And not all drives
work the same: readers
report that some drives
recognize sleep mode and
properly power down, while
others lose the connection
with the Mac, resulting in an
error when it wakes back up.
In macOS 10.15
Catalina and earlier,
the Energy Saver
preference pane’s
Power tab has two
separate settings
you should configure;
in macOS Big Sur,
look to the Battery
preference pane’s
Power Adapter view:- In all versions of
macOS, enable
‘Prevent computer
from sleeping automatically when
the display is off ’. - In Catalina and earlier, disable ‘Put
hard disks to sleep when possible’.
Energy Saver in Mojave offers an array of options; the
top two are the ones to focus on.
Big Sur’s Battery preference pane has a single
setting to modify.