Storage Control Units

You can use DFSMS to manage cache devices.

Continuous availability: Using the continuous availability function, SMS allocates the data set to a dual copy device or to a RAID protected device (support by all RAMAC subsystems). (The 3990 Model 3 or 6 supports dual copy.) For more information, see z/OS DFSMSdfp Storage Administration.
Extended-format data sets: SMS allocates extended-format data sets to a system-managed DASD volume on a 3990 Model 3, Model 6, any RAMAC subsystem, or Enterprise Storage Server®. The data can be allocated on a DASD that supports extended-format data sets. If a device supporting extended-format data sets is not available, the data can be allocated on another device. For more information, see z/OS DFSMS Using Data Sets.
Caching on the IBM 3990 Model 3 or 6: SMS can select the 3990 Model 3 or 6 to provide caching for both read and write operations. The DASD fast write feature of the 3990 Model 3 or 6 provides caching for write operations. Caching enables applications to retrieve data sets more quickly and increases DASD capacity by mixing cached and noncached data on the same volume.
You can use access method services or the ISMF volume application to enable caching and DASD fast write at the volume level.
Caching on the IBM 3880 Model 23: SMS can select the 3880 Model 23 to provide caching for read operations. Caching for a system-managed volume on a 3880 Model 23 is enabled at the volume level, using access method services or the ISMF Volume Application.
Caching on RAMAC subsystems: Caching is always active on the 9393 RAMAC Virtual Array Storage and 9396 RAMAC Scalable Array Storage (RSA). The 9397 RAMAC Electronic Array Storage (REA) is a cache-only subsystem.

Related reading: For information on cache devices, Enterprise Storage Server, and RAMAC Storage Subsystems, see the 3990 Planning, Installation, and Storage Administration Guide.