The z/OS® sysplex is an evolving platform for the large system computing environment. It offers you improved price/performance through cost-effective processor technology and enhanced software. It increases system availability and your potential for doing more work.

A major difference between a sysplex and a conventional large computer system is the improved growth potential and level of availability in a sysplex. The sysplex increases the number of processing units and z/OS operating systems that can cooperate, which in turn increases the amount of work that can be processed.

Because work can be distributed around the sysplex, all systems in the sysplex must have the same security information. Therefore, all systems in a sysplex should use the same RACF® database. Definitions for security categories (members of the CATEGORY profile in the SECDATA general resource class) are likely to cause problems if all systems do not use the same RACF database. For more information on security categories, see z/OS Security Server RACF Security Administrator's Guide.

The coupling facility allows z/OS and other software to share data concurrently among multiple systems in the sysplex with the goal of maintaining a single system image.

A sysplex with a coupling facility significantly changes the way systems can share data. The technology that makes high performance sysplex data sharing possible is a combination of hardware and software services. Data sharing is the ability of concurrent subsystems or application programs to directly access and change the same data while maintaining system integrity.

The goal of RACF in the sysplex is to provide security for the resources of all systems in a comprehensive and centralized way. RACF allows you to use the coupling facility and shared RACF data to help manage the security of resources for all systems in a sysplex.