I have a Mini running Lion Server that has a USB hard drive attached to it for backups. I also have a MBP running Lion that I've set to use that same drive as a remote backup destination over the network.
The remote backups have never failed; however, the local backups from Server to its USB disk only work right after a reboot. When the machine tries to run its next scheduled backup it fails with
Time Machine Error
Unabled to complete backup. An error occurred while creating the backup folder.
Latest successful backup: 12/2/11 at 11:50 PM
at which point I usually reboot the machine and manually run a backup, which succeeds.
Things I've tried
- I've tried googling that error message, but "An error occurred" isn't much to go on.
- I've tried repairing the drive in Disk Utility, but it didn't find any errors.
Other Notes
When I first plugged in this USB disk I told Time Machine to erase it and set it up. It has a GUID Partition Table, one 1TB partition formatted to Case-sensitive, Journaled Mac OS Extended.
What can I do to have my backups run without needing intervention?
tmdiagnose
which collects a ton of diagnostic details to try and isolate issues with the time machine software. It may require help fom Apple or a technician if you aren't familiar with what a normal diagnosis run is or the underlying mechanisms.