As installation requirements change, it may be necessary to update data class, storage group, management class, and storage class definitions in your ACS routines. Definitions for these constructs can be modified using the ISMF ALTER panels.

These updates must be done with caution because volumes that do not require processing after the definitions are changed are not affected by the change, even though they are assigned to the group to which the new definition applies. The updated definitions are used only for volumes entering the system or processed by the system after the change.

If the library is also enabled for outboard policy management, the construct’s policy also needs to be defined outboard at the library with appropriate policy actions, unless default actions are to be used at the library. If the construct’s policy does not exist, the library creates the policy name and uses default actions.

New storage groups may be needed for separation of new types of volumes. In addition to defining the new tape storage groups, it is necessary to modify the ACS routines to use the new tape storage groups.

It is important to consider when you are designing these changes that existing volumes do not change their storage group assignments until they are changed to scratch and then back to private, or until they are manually changed either through ISMF volume ALTER, the CBRXLCS FUNC=CUA interface, or the LIBRARY LMPOLICY command. If a private volume is assigned to a new storage group through the storage group ACS routine, the storage group remains as it was set in the tape configuration database.

As mentioned above, ACS routines may need to be changed to support changes in storage group, data class, management class, or storage class definitions. Defining new storage groups, data classes, management classes, or storage classes has no affect unless the ACS routines are changed to select those new constructs.

ACS routines can be changed to provide initial class defaults for new volumes. Defining new classes does not always mean new values for parameters; a new class can have the same parameters as an existing class. A new class may be created to make the relationship between a class and an application more understandable. This action makes it possible to modify parameters later to fit the needs of one application without affecting other applications.

A Final Note of Caution about Changing SMS Library Definitions: Changing existing library definitions may not affect all volumes associated with those definitions. Only those being stored after the library definitions have been changed are affected.