Optical volumes

A unique volume serial number identifies each optical volume. This unique volume serial number must be unique within the entire installation. No two volumes (regardless of the media type) can have the same volume serial number. The volume serial number must conform to z/OS volume serial number naming conventions as documented in the z/OS MVS JCL Reference.

Because optical volumes can reside either inside libraries or on shelves, the physical procedure for accessing volumes varies according to their location:

When a library-resident optical volume is needed, the system mounts it on an optical disk drive in the optical library containing the volume. If a compatible optical library drive is unavailable (for example, the drive is offline or non-operational), the request to retrieve the object fails.
When a shelf-resident optical volume is needed, the system requests that the volume be mounted on an operator-accessible optical disk drive for a 3995 volume. If an operator-accessible optical disk drive is unavailable (for example, the drive is offline or non-operational), the request to retrieve the object fails. If the requested volume is unavailable, the operator can terminate the request.

Shelf storage can be local to the computer facility and, therefore, accessible to the optical disk drive operator, or it can be located elsewhere. The operator can enter a shelf-resident volume into any compatible optical library by placing the optical disk cartridge into the input/output station of the optical library. However, if there is an outstanding request to mount the volume on an operator-accessible optical disk drive, the attempt to insert the volume into the library is rejected.