Linux for S/390 (IBM z-Series)

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System Administration

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original in en Cüneyt Göksu 

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Database Specialist, working for more than 12 years with all commercial databases on major platforms including Linux!

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S/390 is a robust hardware platform from IBM for large enterprices. Linux is now running on it.

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When the Linux Operating System first appeared on 1991, it's been working on IBM PC Compatibles. Since then it has been ported to many other architectures such as Apple, Atari and 68000 based Amiga computers, Sun Spark workstations; Alpha based personal computers and MIPS, PowerPC, HP PA-RISC and ARM.

S/390 is the name of the mainframe type computer architecture from IBM. This architecture has been used widely with IBM's VM, VSE and z/OS (former MVS and OS/390) operating systems. IBM has chosen Linux, as one of the "Native" Operating System for this solid architecture since 1999.

The most important reason to implement Linux, on the S/390 platform was to consolidat the connectivity among Legacy Applications, Linux Applications and Middleware applications such as web server, mail server, application server, firewall etc.

It is widely said that, Linux works as an API or emulation on the S/390 platform but it is not true, it works as a "native" operating system so that all the hardware capability of this platform is used. Linux Kernel and Common Code are used without any modification and the Linux system structure remains untouched. Only some "adaptations" are required to match and implement S/390 architecture specifics. It works with the ASCII character set instead of EBCIDIC.

Linux Integration to s/390 and the zSeries Achitecture

Linux can be installed in three different ways on a S/390 platform.

In the following diagram those three types of installations are shown:
3 ways to run linux on s/390

If the required number of Linux servers is 15 or less, then the LPAR solution is a good choice. If you need more, 100 or 1000 Linux Images, z/VM will be the answer.
Red Hat, SuSE and Turbolinux are major distributors for S/390 and zSeries.

You can use the links below to download them.

Red Hat:



There are also some distributions in binary. You can get them from the links below.

Distributions for s/390 and zSeries

The Requirements for running Linux on the S/390

Why Linux for s/390 ?

The most important reason is server consolidation.

The three-tiered application architecture can be easily done in two-tiered hardware. (Client / Application Server / Data Server) these 3 classic steps can be joined in the S/390 like (Application Servers / Databases). Hipersocket and Fiberchannel features support the communication subsystem features and connection problems disappear. Legacy Applications became Distributed Applications then web based applications. First, data then applications are distributed everywhere. The number of servers increased enormously. This increase brought some problems:

Those were some of the potential problems in case Linux images are run on different hardware. If all of them are run on a single S/390 platform then the situation changes:

3-tier arch on 2 tier hw