A storage class is a collection of performance goals and device availability requirements that the storage administrator defines. Storage class is a required part of an SMS-managed environment. A storage class provides the criteria that SMS uses in determining an appropriate location to place a data set or object. SMS uses the storage class to select a device according to the following criteria: device performance, the amount of space available on the volume, and how available a data set or object can be on that device.

The RAMAC Virtual Array, the 3990 Storage Control, and the 2105 Enterprise Storage Server® use storage class availability and accessibility attributes to provide a required level of service. SMS ensures that a data set associated with that storage class is allocated to the required hardware.

The storage class coupling facility (CF) caching attributes work with the CF to provide record-level sharing (RLS) for VSAM data sets in a Parallel Sysplex®. When you define a storage class with a CF cache set name, data sets are cached in specific CF cache structures, or buffer pools.

Table 1 shows the types of attributes that you can associate with a storage class.

Related reading: For more information on record-level sharing for VSAM data sets, see VSAM Record-Level Sharing. For more information about defining storage classes, see the z/OS DFSMSdfp Storage Administration.