Set up a massive file transfer to my shiny new backup drive last night and went to bed; I was rather disturbed to come into the office this morning and find an I/O error on the screen, and the OS unable to find the drive. Gleep!
I took the drive out of the USB enclosure, powered down, put it in
Trantor's case, powered up, and was greatly relieved to find the drive up
and running. A thorough fsck and a fresh rsync
confirmed that all data was present and accounted for. I'm guessing it
may have been a glitch somewhere in the external box's USB interface or
the cable. Not going to worry about it much. (eta: power-cycling the
drive enclosure didn't work; I didn't try rebooting or power-cycling the
computer with the drive still external; that would probably have worked, I
was just impatient.)
I'm still trying to resist the temptation to do more work on reorganizing my directory tree and setting up the offsite backups.