Storage groups represent the physical storage managed by SMS. This storage can be collections of DASD volumes, volumes in tape libraries, volumes in optical libraries, or virtual input/output (VIO) storage. A storage group, used with storage classes, separates the logical requirements of accessing data from the physical requirements to store the data. You can use storage group attributes to specify how the system should manage the storage group. You use the storage group ACS routine to assign a new data set or object to a storage group. You can assign multiple candidate storage groups (except for objects), in which case the system chooses a specific storage group from your list. Storage group definitions are not apparent to users. Only you, as storage administrator, can define, alter, or display storage group definitions.

A storage group can be VIO, dummy, copy pool backup, pool, object, object backup, or tape. VIO storage groups are not associated with volumes. Dummy storage groups are associated with nonexistent volumes. When defining pool storage groups, the actual, physical paths connecting systems to DASD volumes must match the desired logical paths specified in the storage group definitions. Merely establishing a physical connection from a system to a DASD volume does not provide access. Within the storage group definition, you must specify which systems have access to which storage groups, and which storage groups have access to which DASD volumes. Likewise, merely defining a system to have access to a DASD volume does not establish a physical connection. The physical connection must exist.

For tape storage groups, one or more tape libraries are associated with them. Connectivity is defined at both the library level and the storage group level. If a storage group is connected to certain systems, then any libraries associated with that storage group must be connected to the same systems. Scratch volumes are added to storage groups when they are used. Private volumes can be added when they are entered in a library. Private volumes are removed from a storage group and returned to the common scratch pool when they are returned to scratch status.

For more information on how to use storage groups with objects, see Object and object backup storage groups.