Establishing a storage management policy

Each installation defines a storage management policy that allows effective object storage management without requiring user intervention. Through the use of Interactive Storage Management Facility (ISMF), the storage administrator and system programmer define an installation storage management policy in an Storage Management Subsystem (SMS) configuration. OAM then manages object storage according to the currently active policy.

OAM defines the management policy parameters in the SMS constructs of management class, storage class, storage group, and data class. The constructs include the following specifications:

Object retention rates
Media on which OAM stores object collections
Legal requirements for object retention
Retrieval response time
Location of object collections in the storage hierarchy
How long OAM should hold the object collection at that level in the hierarchy
Whether you need one or two backup copies of an object
Media type to which OAM should direct backup copies of objects
Affiliation of libraries with relevant storage groups

Refer to z/OS DFSMS Using the Interactive Storage Management Facility for general information on using ISMF. Refer to z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support and z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Tape Libraries for specifics of using ISMF within tape and optical storage environments to set up the management policy parameters.

Objects in OAM reside in a storage hierarchy that can include disk (DB2 or file system), optical volumes, and tape volumes. Optical and tape volumes can be library-resident or shelf-resident. The primary copies of objects can be stored to disk (DB2 or file system), optical volumes, or tape volumes; while backup copies of objects can only be stored to optical or tape volumes. OAM manages the storage hierarchy at the system level by using SMS management class, storage class, storage group, and data class constructs. The constructs specify the management policy parameters that define the performance, retention, and backup requirements. OAM associates these parameters with every object that it stores. The storage administrator defines the associations through automatic class selection (ACS) routines. The constructs are as follows:

Management Class: Defines backup, retention, and class transition characteristics for objects. A management class contains parameters that define the need for making one or two backup copies of the object. They also determine the default lifetime of an object, and an event that can cause the assignment of a new management class, storage class, or both. OAM uses these parameters to create one or two backup copies of an object, to delete an object automatically, and to invoke an automatic class selection (ACS) routine when the specified transition event occurs. An ACS routine defines the management policy for a collection based on a combination of these constructs.
Storage Class: Defines the level of service for an object, which is independent of the physical device or medium that contains the object. A storage class contains parameters that define performance characteristics and availability requirements for an object. OAM uses these parameters to determine where to place objects in the storage hierarchy (disk sublevel 1 (DB2), disk sublevel 2 (file system), optical, tape sublevel 1, or tape sublevel 2).
Storage Group: Allows the user to define a storage hierarchy and to manage that hierarchy as if it were one large storage area. You may assign a first and a second Object Backup storage group to a specific Object storage group, or to all Object storage groups, by including SETOSMC statements in the CBROAMxx parmlib member. For more information on multiple object backup specification and the SETOSMC command, refer to z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support.
Data Class: Defines tape-related information for scratch tape volumes that are allocated for OAM objects. The information defined by the data class includes the retention period, tape expiration date, tape compaction, recording technology, and media type.
Note: You must update the data class's ACS routine to ensure that OAM does not assign a DATACLASS parameter to the OAM object-to-tape data sets. These data sets are named OAM.PRIMARY.DATA, OAM.BACKUP.DATA, or OAM.BACKUP2.DATA. You may associate a DATACLASS with a scratch tape volume through the SETOAM command of the CBROAMxx parmlib member when the scratch tape volume is allocated. Allowing the data class's ACS routine to override or change the DATACLASS value provided by the SETOAM command can cause unexpected results. This may interfere with the storage management expectations for the installation. For more information on object-to-tape support and the SETOAM command, refer to z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Object Support. You should consider how your application affects the administration of the objects it stores.

To control the management of an object, assign it to a collection whose management policy is the same as that required by the new object. There is no explicit way to tell OAM where to store a particular object.

For more information on z/OS constructs, refer to the z/OS DFSMSdfp Storage Administration manual.