After the second of the two recent power outages, the outlet powering Chiara's external drive for local backups didn't come back. The modification to the backup script I made correctly identified that the drive wasn't mounted, and happily logged its absence and didn't try to stuff the internal drive with a copy of itself. However, I hadn't checked the logs to see if the backups were proceeding until today... maybe I should set up an email alert for these, too.
I plugged the external drive into a live outlet, and mounted the 40mBackup drive with: sudo udisks --mount /dev/sdc1, which is a helpful command that puts the drive at /media/40mBackup as it should be, based on the drive label.
sudo udisks --mount /dev/sdc1
The /cvs/cds backup is now proceeding, to make up for lost time.