IBM Parallel Sysplex: Difference between revisions

Revision as of 21:34, 7 June 2006

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In computing, a '''Parallel [[Sysplex]]''' is a [[computer cluster|cluster]] of [[IBM mainframe]]s acting together in a single system image, usually with [[z/OS]]. A Parallel Sysplex combines data sharing (typically using [[Peer to Peer Remote Copy]]) and [[parallel computing]] to allow a cluster of up to 32 computers to share a workload for [[high performance computing|high performance]] and [[high availability]]. Parallel Sysplex provides [[horizontal scaling]].

The forerunner of theto Parallel Sysplex was '''Virtual Coupling''', a technique which allowed up to 12 [[IBM 3090]] systems to execute jobs in parallel. The true Parallel Sysplex was introduced with then-new mainframe models in April, [[1994]]. IBM continues to improve and enhance Parallel Sysplex.

Major components of a Parallel Sysplex include:

* [[Coupling Facility]] (CF or ICF) hardware, allowing multiple processors to share, cache, update, and balance data access;

* A [[Sysplex Timer]]s or [[Server Time Protocol]] to synchronize the clocks of all member systems.;

* High speed, high quality, redundant cabling;

* Software ([[operating system]] services and, usually, [[middleware]] such as [[DB2]]).

The Coupling Facility may be either a dedicated external system (a small mainframe specially configured with only coupling facility processors) or integral processors on the mainframes themselves configured as ICFs (Internal Coupling Facilities). Both are popular — there are minor technical advantages and disadvantages between external CF and ICF installations.

{{update}}IBM will replace the Sysplex Timer with [[Server Time Protocol]] starting in late 2005.

A Parallel Sysplex has at least two CFs or ICFs for redundancy (or at least one of each). Every mainframe participating in a Parallel Sysplex does not need an ICF or its own external CF — mainframes merely attach, via cables, to the external CFs or ICFs.

Server Time Protocol (STP) replaced the Sysplex Timers beginning in 2005 for newer mainframe models. While the Sysplex Timers are physically separate machines, STP is an integral feature within the mainframe itself. With STP and ICFs it is now possible (and common) to construct a complete Parallel Sysplex installation solely with two mainframes and cabling. Moreover, a single mainframe can contain the internal equivalent of a complete physical Parallel Sysplex, so there is no technical requirement to have an actual Parallel Sysplex for application testing and development purposes.

==See also==