Defining your storage management policy

SMS manages an installation’s storage according to the currently active storage management policy. Through ISMF, you define an installation storage management policy in an SMS configuration. An SMS configuration contains the following:

Base configuration information
Classes and groups
Automatic class selection (ACS) routines
Optical library and drive definitions
Tape library definitions

The base configuration identifies the systems that the SMS configuration manages. These systems constitute an SMS complex. The base configuration also contains installation defaults.

You can define more than one control data set, but only one at a time controls SMS. Each control data set defined for SMS is called a source control data set (SCDS). The control data set that is in effect at a given time is the active control data set (ACDS).

SMS classes and groups are lists of traits and characteristics that are associated with or assigned to data sets, objects and volumes. An SMS configuration can contain the following types of classes and groups:

Storage group: Use this to define a list of volumes and manage them as if they were one large, single volume. SMS applies the properties you assign to a storage group to all the volumes within the storage group.
Management class: Use this to define different levels of migration, backup and retention services. Through management class, you can associate a level of service with a data set or object that is independent of the physical location of the data set or object. Also, you can identify an object characteristic that might trigger a class transition.
Storage class: Use this to define different levels of performance and availability services. Through storage class, you can separate the level of service for a data set or object from physical device characteristics. You can also separate the level of service for an object with different storage classes used to place objects at various levels of the storage hierarchy.
Data class: Use this to define allocation defaults. Through data class, you can simplify and standardize the allocation of new data sets.
Aggregate group: Use this to define groups of data sets for the purpose of backing up or recovering all data sets in a group in a single operation.
Copy pool: Use this to define a pool of storage groups to be processed collectively for fast replication operations.

An SMS configuration can contain multiple constructs of each type. Data sets managed by SMS are called system-managed. Each system-managed data set or object must reside in a storage group. The system-managed data sets must have a storage class, and might also have a management class and a data class. The objects must have a storage class and a management class.

You can assign the same name to various SMS classes and a storage group. For example, a data class and a storage class can have the same name.

ACS routines determine the SMS classes and storage groups for data sets and objects. You can also use ACS routines to control the transition of data sets to and from SMS management (objects are always SMS-managed).