why has it been unmounted?
do you mean you have shutdown your mac and disconnected it?
if not then is it still connected to your mac but just not mounted?
how do you know its doing something with the drives? can you hear them?
is it not going into standby? (if you have disconnected it)
are the status lights next to the drives solid green or flashing green/yellow ?
As a “technical user” i would have thought you may have given us a few more details about your issue ?[hr]
For rebuilds/change in protection levels - it does have a progress meter in the dashboard - as these are the things you cant interrupt.
It would make zero sense to even try and have a progress meter for on-going housekeeping.