8.2.6.2. Testing Backups
Every type of backup should be tested on a periodic basis to make sure that data can be read from it. It is a fact that sometimes backups are performed that are, for one reason or another, unreadable. The unfortunate part in all this is that many times it is not realized until data has been lost and must be restored from backup.
The reasons for this can range from changes in tape drive head alignment, misconfigured backup software, and operator error. No matter what the cause, without periodic testing you cannot be sure that you are actually generating backups from which data can be restored at some later time.