You can cascade (link) multiple stand-alone tape drives together to create one logical drive. By cascading the tape drives, backup jobs can automatically "roll" to the media in the next tape drive when the media is filled. Although multiple tape drives are linked to form the cascaded drive pool, only the name of the cascaded drive pool is listed as the destination device when a backup job is created.
Tape drives in a cascaded drive pool are not available for concurrent operations. Only one tape drive is used at a time. The next tape drive in the cascaded drive pool is used only when a backup job fills the current media, or when the next job requires a different media (such as an overwrite job).
Use cascaded drive pools to run unattended backup jobs, or to make sure a large backup job will complete without operator intervention. You may also want to use cascaded drive pools if you want data from a job or group of jobs to reside on the same tape family.