Managing coupling facility resources

Sysplex support for a coupling facility satisfies customers' requirements for:
  • Data sharing across the systems in a sysplex
  • Resource sharing across the systems in a sysplex
  • Maintaining the integrity and consistency of shared data
  • Maintaining the availability of a sysplex.

The coupling facility makes data sharing possible by allowing data to be accessed throughout a sysplex with assurance that the data will not be corrupted and that the data will be consistent among all sharing users. The coupling facility provides the medium in which users of coupling facility structures can reconstruct shared data should a failure occur and can be used to assist in the isolation of failing systems.

The coupling facility is a shareable storage medium, but not what we usually consider a shared storage device. Rather, a coupling facility is licensed internal code (LIC) running in a special type of PR/SM logical partition (LPAR) in certain z/Series and S/390® processors. A coupling facility can be shared by the systems in one sysplex only; it cannot be shared simultaneously by multiple sysplexes.

The following topics describe what a coupling facility is and how to include one or more coupling facilities in your sysplex: