You need to maintain a large and easily accessible stock of backup tapes, because you can never be sure ahead of time exactly how many tapes you need for each backup. The number of tapes you need depends upon whether you are performing a full or partial backup and how much data is stored on your system.
Using new tapes ensures the best possible data integrity. You can, however, safely use used or scratch tapes if they are in good condition, and if they contain outdated information.
The information on a used tape is outdated if the purge date on the label has passed. To judge whether a used tape is in good condition, check the number written below "CYCLE" on the tape label; it tells you how many times a tape has been used. Tapes wear out and become unreliable after being used many times.
