Planning storage groups for OAM object collections

For each major application that processes objects, one or more object collections must be defined to provide for the storing, cataloging, and retrieval of objects used by that application. Each object collection must be assigned to a storage group by the storage group ACS routine. Multiple collections can be assigned to the same storage group.

A storage group for OAM object collections provides a storage hierarchy containing a DB2® table for the object directory for objects in the storage group, DB2 tables for storage of objects on disk sublevel 1 (DB2 tables), disk sublevel 2 (file system), optical volumes for the storage of objects on optical media, and tape volumes for the storage of objects on tape media. Tape volumes can be defined as sublevel 1 or sublevel 2.

Each object that OAM stores is assigned a storage class and a management class. OAM uses the storage class to determine the initial placement of an object in the OAM object storage hierarchy. OAM also uses the storage class during the OSMC storage management cycle to determine the correct placement of the object when the storage management cycle processes that object. OAM uses the Initial Access Response (IARS) parameter in the storage class to determine if a primary copy of an object is stored on disk (DB2 tables or a file system) or on removable media (optical or tape). If the IARS parameter in the storage class that is assigned to the object is zero, the primary copy of the object is stored on disk. If the IARS parameter is nonzero, the primary object is stored on removable media.

If the IARS parameter specifies that removable media is to be used, the Sustained Data Rate (SDR) parameter of the storage class determines which removable media, optical or tape, is used to accept the primary copy of the object. If the SDR parameter of the storage class is greater than or equal to three (≥3), the primary copy of the object is stored on a tape volume. If the SDR parameter of the storage class is less than three (<3), the primary copy of the object is stored on an optical disk volume.

If the IARS and SDR parameters, taken together, specify either disk or tape media, the OAM Sublevel (OSL) parameter of the storage class determines which disk or tape sublevel is to be used to accept the primary copy of the object. If it has been determined that the primary copy of the object is to be stored on disk, then if the OSL parameter of the storage class equals 1, the primary copy of the object is stored on disk sublevel 1 (DB2 tables), whereas if the OSL parameter of the storage class equals 2, the primary copy of the object is stored on disk sublevel 2 (file system).

Similarly, if it has been determined that the primary copy of the object is to be stored on tape, then if the OSL parameter of the storage class equals 1, the primary copy of the object is stored on a tape sublevel 1 volume. If the OSL parameter of the storage class equals 2, the primary copy of the object is stored on a tape sublevel 2 volume.

Table 1 provides a summary of how the IARS, SDR, and OSL values determine the initial placement of an object in the OAM object storage hierarchy.

Table 1. Summary of media selection for object storage
IARS value	SDR value	OSL value	Where object is stored
0	N/A	1	disk sublevel 1 (DB2 tables)
0	N/A	2	disk sublevel 2 (file system)
non-zero	<3	N/A	optical disk
non-zero	≥3	1	tape sublevel 1
non-zero	≥3	2	tape sublevel 2

Before you actually define your storage groups, you should gather the following information:

Existing I/O hardware configuration
Projected hardware requirements
Estimated general requirements of user groups
Anticipated security requirements
Backup and recovery requirements
Object sizes
Required system access, based on both shared data requirements and the needs of user groups
The number of systems to which the storage group is connected

See z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support for more information on planning for objects.