Storage classes for objects

For OAM, storage classes separate performance objectives from physical storage and determines where the object resides in the storage hierarchy.

OAM uses storage classes to logically represent the level of service required by an object. This could result in placement of the object on one of these types of physical storage in its object storage hierarchy:

Direct access storage devices (DB2® object tables)
File system (NFS or zFS)
Optical volumes
Tape volumes

The default storage class for an object is defined in the catalog entry for the object collection to which the object belongs. If the default management class is not available from the catalog entry, OAM uses the collection entry in the DB2 table and updates the catalog entry. The default storage class is assigned by the storage class ACS routine when the first object is stored in the collection.

Note: If the catalog entry for the collection does not exist, but a DB2 table entry does, this is an error. If neither exist, both are created during a first time store to a new collection, using the storage class, management class, and storage group from the ACS routine.

See z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support for a more specific discussion of how to use storage classes with objects.