A backup tape that cannot be read is useless. So, periodically clean and check your tape drives to ensure correct operation. See your hardware manuals for instructions on procedures for cleaning a tape drive. You can check your tape hardware by doing either of the following:
Copying some files to the tape, reading the files back, and then comparing the original files with the copied files.
Using the -v option of the ufsdump command to verify the contents of the media with the source file system. The file system must be unmounted or completely idle for the -v option to be effective.
Be aware that hardware can fail in ways that the system does not report.
Always label your tapes after a backup. If you are using a backup strategy similar to the strategies suggested in Chapter 24, Backing Up and Restoring UFS File Systems (Overview), you should indicate on the label “Tape A,” “Tape B,” and so forth. This label should never change. Every time you do a backup, make another tape label that contains the following information:
The backup date
The name of the machine and file system that is backed up
The backup level
The tape number (1 of n, if the backup spans multiple volumes)
Any information specific to your site
Store your tapes in a dust-free safe location, away from magnetic equipment. Some sites store archived tapes in fireproof cabinets at remote locations.
You should create and maintain a log that tracks which media (tape volume) stores each job (backup) and the location of each backed-up file.