The storage class construct enables storage administrators to separate the logical requirements for accessing data from the physical requirements for storing data. Storage class represents the level of service (performance objectives and availability requirements) for an object.

Every object is assigned to a storage class when it is created; therefore, every object is SMS-managed. This assignment determines where the object initially resides in the object storage hierarchy (DB2 sublevel, file system sublevel, optical, tape sublevel 1, and tape sublevel 2). See Figure 1 for a diagram of this process. The assignment can change as part of a class transition or as the result of an explicit application request (OSREQ CHANGE).