Introduction to tape library management

The Object Access Method (OAM) is a component of DFSMSdfp, the base of the storage management system (SMS) of DFSMS. OAM uses the concepts of system-managed storage, introduced by SMS, to manage, maintain, and verify tape volumes and tape libraries within a tape storage environment.

The management of data on tape volumes is not discussed in this manual. See z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support for information on OAM's role in the storage of objects on tape volumes. Also, see z/OS DFSMSrmm Managing and Using Removable Media for information on of DFSMSrmm's role in the management data on tape volumes.

In general, a tape library is a set of tape volumes and the set of tape drives where those volumes may be mounted. The relationship between tape drives and tape volumes is exclusive; a tape volume residing in a library (library-resident tape volume) can only be mounted on a tape drive contained in that library (library-resident tape drive), and a library-resident tape drive can only be used to mount a tape volume which resides in the same library. A tape library can consist of one or more tape systems.

When a volume is entered into a tape library, it is assigned to a tape storage group. A tape library can contain volumes from multiple storage groups, and a storage group can reside in up to eight libraries.

As new tape data sets are created, the installation allocates data sets to tape volumes in an SMS-managed tape library by associating one or more tape storage group names (using the SMS storage group ACS routine) with the allocation request. DFSMS ensures that only tape devices within the tape libraries associated with the tape storage groups are allocated to the request. Existing tape data sets on library-resident volumes are allocated to tape drives within the library where the volume resides.