z/Series is the current large computer architecture of the company IBM. In relation to predecessor architecture zSeries is characterised S/390 particularly by the 64-Bit-Adressierung. Older programs, which run still with 32-Bit or 24-Bit-Adressierung, are likewise still supported.

The strengths of this platform lie in the reliability of the hardware as well as in the Virtualisierung. The hardware is completely redundantly laid out, so that losses are extremely improbable. The current models are in the situation, with maximally 30 LPARs different operating systems to boats.

At present there is 4 types, the z800, the z900 (models are since approx. September 2000 on the market), the z890 and the z990 (for spring 2004). In September 2005 the company IBM announced the newest model, which breaks however with the designation system z9 109 with the past name tradition.

Computers that zSeries do not have own non removable disks, but are connected by ESCON, FICON or Fibre Channel with STORAGE servers or a SAN.

Architecture

The development z/Architektur led the functions of the preceding systems from S/360 and S/370 across many intermediate steps, was always maintained and extended. Thus with the step from ESA/390 to z/Architektur the following important extensions were made:

• General and control register have a length of 64 bits
• There are 64 bits, to 31 bits and 24 bits an addressing mode
• Tables for the dynamic ratio of 64 bits addresses are extended by 3 levels

A substantial difference between ESA/390 and z/Architektur is of z/OS in 64 bits mode no longer usable Expanded STORAGE. This together with the S/370 XA-architecture because of at that time on 2 GB limited addressability introduced. At that time this represented a favorable way main storage to extend. In the momentarily available zSeries models main storage up to 64 GB can cover.

A further interesting development characteristic represents the Channel subsystem. Transmission rate rose from first 4,5 MB/s over 17 MB/s with the ESCON channels to meanwhile over 100 MB/s with the glass fiber channels (FICON).

The CCU

Hardware

Software

The CCU is the switching center of the entire system and contains

• 16 general PUR-float register
• 16 floating decimal point registers
• 16 ACCESS registers
• 16 control registers
• 1 Floating POINT control register
• 1 Program status Word

On computers that zSeries the operating systems run z/OS, z/VM, z/VSE, zTPF and zLinux. Architecture is characterised also by its own term world, then for example the boat process is called IPL (initial Program load). One calls the restart of the complete server (switch on) also POR (power on RESET).

With Hercules an emulator is available, which makes it possible to emulate a zSeries system under Windows or Linux. There IBM neither z/OS nor z/VM for this emulator licensed, could be tested here if necessary the installation of a Linux. There is however still another free version of MVS (3,8, the last version in the 24-Bit-Modus before MVS/XA), whose source text is available in the Web and may on Hercules legally be installed.

At most common emulator for the S/390 architecture is world-wide FLEX-ES. The product makes the enterprise possible of many current and also already replaced S/390 of operating systems on Intel a computer. Contrary to Hercules licensed IBM many S/390 of operating systems for the employment under FLEX-ES.

See also

• System z9
• iSeries
• pSeries
• xSeries

Related links

• Web offer to the product series with IBM (English)
• zSeries Principles OF operation (English)
• MVS 3,8 Freeware (English)

Articles in category "ZSeries"

We found here 3 articles.

Related Websites

We found here 4 related websites.

• IBM eServer zSeries 900
  At the core of many infrastructures is the IBM eServer zSeries 900 (z900) powered by z/OS.


• IBM eserver zSeries Mainframe Servers
  IBM home page for current mainframe computer systems, with links to an overview, software, operating...


• IBM eServer: Linux on System z9 & zSeries
  Linux on System z9 and zSeries - An ideal foundation for on demand operating environments. Informational landing page with links to more information.


• Linux Community Development System
  The Service provides you with access to a Linux on zSeries environment for the purpose of providing the Open Source community with a platform to develop, ...