Object access method support for tape libraries

OAM uses system-managed storage concepts within the SMS component of DFSMS to provide the management facilities for the physical movement and tracking of the tape volumes used within tape libraries.

The three components of OAM are:
  • Object Storage and Retrieval (OSR)
  • OAM Storage Management Component (OSMC)
  • Library Control System (LCS)

When using OAM's object support, it is important to note that there is now a potential for a multiple OAM configuration. A multiple OAM configuration allows you to have multiple “Instances” of OAM on a single system. An instance consists of an OAM subsystem and an associated OAM address space. In a multiple OAM configuration, an OAM address space is used either for Tape Library related processing or for Object processing, and it is possible to have multiple OAM address spaces on a single z/OS system. You can also have up to two Object address spaces and one separate Tape Library address space. A classic OAM configuration supports a single OAM instance per system and can be used for both object related processing and tape library related processing. This is the original OAM configuration support prior to the introduction of the "multiple OAM configuration" support. For more information on possible OAM configurations, see z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support.

The manual covers the use of the LCS component of OAM in support of tape libraries. For information on the roles of OSR, OSMC, and LCS in support of object data, see z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support.

OAM provides the following services in support of tape libraries:
  • Cartridge entry, eject, audit, mount, and dismount processing
  • Operator command processing
  • Tape configuration database (TCDB) management
  • A set of tape library-related services that might be used by the installation (see Library control system (LCS) external services)
  • Installation exits that influence tape processing at four critical points:
    • Entering a cartridge into a tape library, or importing logical volumes into a virtual tape system (VTS)—CBRUXENT
    • Ejecting a cartridge from a tape library, or exporting logical volumes from a VTS—CBRUXEJC
    • Changing the use attribute of a tape cartridge—CBRUXCUA
    • Allowing the installation to enter a nonlibrary-resident cartridge into a tape library during allocation processing—CBRUXVNL

    See Installation exits for more information on these installation exits.

  • Unsolicited attention message processing.
  • CBROAMxx PARMLIB support (SETTLIB) for tuning various aspects of the system managed tape library support (for example, cartridge entry, scratch threshold messaging and automated retry logic for mount failures).
Recommendation: Only a subset of the functions above actually run within the OAM address space (entry, eject, audit, and unsolicited attention message processing). Cartridge mount and dismount activity (job processing) does not require the OAM address space. However, since job processing often results in volumes that are entered and error and status messages that are displayed, run the installation with the OAM address space active whenever possible.