You can use private volumes by explicitly requesting a specific volume serial number.

All scratch tapes within a library are contained within common scratch pools—one for each type of media in the library—and cannot be explicitly mounted by specifying a volume serial number. See SCRATCH THRESHOLD for more information on scratch threshold processing. Once a tape is removed from a common scratch pool, it is assigned to a storage group, the volume use attribute is changed to private, and it remains private until it is returned to scratch status.

Private tapes are returned to the common scratch pool through an ISMF ALTER request, through the use of the Library Control System (LCS) external services change use attribute function, or by a tape management system.

In an MTL environment, because there is no outboard category assignment and outboard selection of a particular scratch volume, the operator, as in the stand-alone environment, is free to mount an appropriate scratch volume. Additionally, in an MTL environment, the scratch volume mounted must be of the appropriate media type for the request, and it must have previously been entered into the library as a scratch volume in the MTL in which the allocated drive resides. The ability of the operator to mount a scratch volume enables volume pooling to work in a fashion similar to that of the stand-alone environment. See your tape management system for specific implementation details about volume pooling and the MTL.

If an MTL resident scratch volume is mounted outside of the MTL environment on a stand-alone device, the volume will remain scratch in the tape configuration database.

OAM does not keep volume records in the tape configuration database (TCDB) for the physical stacked volumes used in the VTS. However, when logical volumes are exported from a VTS, the stacked volumes containing the logical volumes are reported through messages and passed to the cartridge eject installation exit (CBRUXEJC). This is done so that a tape management system can track the physical stacked volume on which an exported logical volume resides.

Outboard policy management enables you to better manage your VTS stacked and logical volumes. With this support, the SMS construct names that are associated with a volume (storage class, storage group, management class, and data class) are sent to the library. When file sequence 1 is written (DISP = NEW), the 8-character SMS construct names (as assigned through your ACS routines) are passed to the library. At the library, you can define outboard policy actions for each construct name, enabling you and the VTS to better manage your volumes. For example, through the storage group policy and physical volume pooling, you now have the ability to group logical volumes with common characteristics on a set of physical stacked volumes.

Special care must be taken to mount a volume with a duplicate volume serial number outside of an IBM managed tape library. When the duplicate volume serial number is requested, if a volume record exists for that volume in the tape configuration database indicating that the volume is library resident, the allocation for that request will be directed to the library in which the volume resides. To direct the allocation of the duplicate volume to a stand-alone device, a special reserved storage class name, DUPT@SMS, can be specified with the storage class parameter on the JCL with DISP=OLD. This will force allocation of this request to a stand-alone device.

A tape management system such as DFSMSrmm can provide support for managing duplicate volumes while they are both in the library and system-managed. DFSMSrmm duplicate volume support allows you to have different barcoded labels on volumes that have the same VOL1 label volume serial number.