Automatic volume recognition

Under automatic volume recognition (AVR), the operator can premount volumes on any unused drives. The volumes must be labeled (standard or nonstandard). The system records the volume and unit information, and assigns the drives when that volume is requested.

Note: If the drive is needed earlier for another request, then the volume will be unloaded.

AVR checks the tape label during allocation by the scheduler, and records the volume serial number. This action merely determines which volumes are mounted on which devices; AVR does not verify or reject the volumes based on their serial numbers. The following conditions cause the volume to be unloaded:

The volume is unlabeled.
The volume has a nonstandard label and either there was no installation exit or the installation exit rejected the volume.
The volume serial number is a duplicate of one that is already mounted.

In an automated tape library, a mismatch between the external volume label and the tape volume label causes an error. When AVR detects an error, it causes the volume to be unloaded with a message identifying the error.