My company recently wasted a lot of time restoring data from corrupted USB disk backups. Everyone here is now keen to prevent the same happening again - but before buying the $5K tape drive now recommended I wanted to investigate a bit further.
The data recovery company that helped restore our data told our engineer that backing up to USB disk is a stupid idea. I wanted to find out why this might be, but have so far failed to find any likely reason. The only issues that I can think of that might affect these backups are
- Physical damage to the disks. Although disks are less robust than tapes, it seems unlikely as the disks themselves are readable and were not badly treated.
- Failing to eject the device before unplugging (also seems unlikely, as the disks would in any case typically be unplugged long after the backup finished)
Does anybody know of any fundamental problems either with backing up via USB, and/or to disk? Is NAS any better? My suspicion is that it was the fact that backups were never checked (no test restores ever done) that was the problem, not the fact that the backups were on disk or performed via USB.
For background... :
The fault we experienced: One day the server crashed due to a motherboard fault, resulting in corrupted data on a RAID disk pair. When it came to restoring the server, we found that the USB backup disks (which had apparently verified ok) were mostly unreadable. On the one BKF backup that I checked it seems that it became unreadable was the MS Exchange database folder. We managed to restore data using the rather clunky but usable 'systools BKF repair'.
Our precautions against data loss consisted of
- RAID disk pairs, with windows sever set to record 'previous versions' of files
- Weekly backup/verify of complete SBS 2003 server (~200GB) to 500GB USB disks
- Daily incremental internet backup of user data (~60GB)