Selection of control unit and device

The choice of the DASD device and control unit for the RACF® database can affect the performance and reliability of RACF and the system.

Guidelines: For best performance, follow these guidelines for selecting a DASD control unit and device for the RACF database:

Do not place the RACF database on the same control unit or device as other frequently used data sets. Placing it on such a device degrades both system and RACF performance.
Do not place the RACF database on the same control unit or device as other data sets that might have RESERVEs issued against them, such as catalogs and VSAM data sets.
If the device activity, because of RACF database I/O, warrants it, consider placing the RACF database behind a cached control unit such as the IBM® 3990-3.