IBM Parallel Sysplex

In computing, a Parallel Sysplex is a cluster of IBM mainframes acting together as a single system image with z/OS.

In 1990, IBM mainframe computers introduced the concept of a Systems Complex, commonly called a Sysplex, with MVS/ESA SPV4.1.

The CF contains Lock, List, and Cache structures to help with serialization, message passing, and buffer consistency between multiple LPARs.

[10] It is recommended that a Parallel Sysplex has at least two CFs and/or ICFs for redundancy, especially in a production data sharing environment.

Server Time Protocol (STP) replaced the Sysplex Timers beginning in 2005 for System z mainframe models z990 and newer.

Moreover, a single mainframe can contain the internal equivalent of a complete physical Parallel Sysplex, useful for application testing and development purposes.