IBM System z

IBM System z (officially "IBM z Systems") is a family name used by IBM for all of its mainframe computers. In 2000, IBM renamed the existing System/390 to IBM eServer zSeries with the e depicted in IBM's red trademarked symbol, but because no specific machine names were changed for System/390, the zSeries in common use refers only to the z900 and z990 generations of mainframes. In April 2006, with another generation of products, the official family was changed to IBM System z, which now includes both older IBM eServer zSeries, the IBM System z9 models, the IBM System z10 models, and the newer IBM zEnterprise. The zSeries, System z and zEnterprise families were named for their availability – z stands for zero downtime. The systems are built with spare components capable of hot failovers to ensure continuous operations. The System z family maintains full backward compatibility. In effect, current systems are the direct, lineal descendants of System/360, announced in 1964, and the System/370 from the 1970s. Many applications written for these systems can still run unmodified on the newest System z over five decades later.

IBM System z9

IBM System z9 is a line of IBM mainframe computers. The first models were available on September 16, 2005. The System z9 also marks the end of the previously used eServer zSeries naming convention. It was also the last mainframe computer that NASA ever used.

Background

System z9 is a mainframe using the z/Architecture, previously known as ESAME. z/Architecture is a 64-bit architecture which replaces the previous 31-bit-addressing/32-bit-data ESA/390 architecture while remaining completely compatible with it as well as the older 24-bit-addressing/32-bit-data System/360 architecture. The primary advantage of this arrangement is that intensive applications like DB2 are no longer bounded by 31-bit memory restrictions while older applications can run without modifications.

Name change

With the announcement of the System z9 Business Class server, IBM has renamed the System z9 109 as the System z9 Enterprise Class server. IBM documentation abbreviates them as the z9 BC and z9 EC, respectively.

IBM System z10

IBM System z10 is a line of IBM mainframes. The z10 Enterprise Class (EC) was announced on February 26, 2008. On October 21, 2008, IBM announced the z10 Business Class (BC), a scaled-down version of the z10 EC. The System z10 represents the first model family powered by the z10 quad core processing engine. Its successors are the zEnterprise System models introduced in 2010 and 2012.

Features

Processors

The number of "characterizable" (or configurable) processing units (PUs) is indicated in the hardware model designation (e.g., the E26 has 26 characterizable PUs). Depending on the capacity model, a PU can be characterized as a Central Processor (CP), Integrated Facility for Linux (IFL) processor, z Application Assist Processor (zAAP), z10 Integrated Information Processor (zIIP), or Internal Coupling Facility (ICF) processor. (The specialty processors are all identical and IBM locks out certain functions based on what the processor is characterized as.) It is also possible to configure additional System Assist Processors, but most customers find the mandatory minimum SAP allocation sufficient.