You can use multiple backup media to back up in parallel or to restore from parallel backup media. For this purpose you define a group of parallel backup media that is identified by a single, grouped media name.
Parallel backup media are simultaneously written or read by the database instance. This increases data throughput - and thus the speed of backup or restore.
The general database parameter MAXBACKUPDEVS specifies the maximum possible number of files or tape devices in a group of parallel backup media.