A few years ago a colleague related a story to me where the main ERP system crashed. RAID was employed but there were multiple hard disk failures. The system administrator spent several hours trying to restore the data from the disks but after a few hours called the supervisor to report the problem. The supervisor directed the system administrator to restore from backup tapes.

"Uh, I can't do that" was the reply.

"Why not?"

"The backups hadn't worked in a few months".

"Why didn't you tell me that before?"