You should create a storage class for each level of service provided by the installation. Before you actually define storage classes, you need to identify the hardware available in your installation. The fastest response time and data sharing for VSAM data are obtained from the coupling facility (CF). The fastest response time for DASD data sets is obtained from cached devices, such as devices behind a 3990 Storage Control with cache active, an IBM® RAMAC Virtual Array, or an IBM ESS. Object storage classes should reflect the hardware available in the object storage hierarchy.