It is also helpful to have at least two tape drives, and check the backup tapes against both. Early in my career, we had a storm that caused an electrical surg

It is also helpful to have at least two tape drives, and check the backup tapes against both. Early in my career, we had a storm that caused an electrical surge. In spite of the power protection, it damaged the tape drive on the main server (unknown to us at the time). The entire rest of the system (CPU, RAM, hard drives (RLL!)) were fine. Listening to the backups being run, I noticed it sounded a little different. Eventually I determined that the tape drive (old QIC, maybe 40MB capacity?) worked, but it would not switch tracks when reading / writing. So the backup ran, but it just overwrite the same track rather than write to subsequent tracks. A short backup / restore wouldn't have caught the problem, it was necessary to try to read the whole backup to see. This wasn't caught for a while, so all the backups were mostly useless.