First Deployments on Linux for the Mainframe
First deployments on Linux for the mainframe
The first deployments on Linux for the mainframe were file and print servers. And the first piece of software that became popular was Samba. The first large commercial customer for SUSE Linux Enterprise Server for S/390 was Telia, the largest telecommunications company in Sweden.
The marketing literature for SUSE Linux Enterprise Server for S/390, published in 2000, indicated that the operating system supported IBM's G5 and G6 mainframe servers as well as the IBM Multiprise 3000. Shortly thereafter, support for the zSeries z900 in 32-bit mode was announced. SUSE Linux Enterprise Server for S/390 could run in a logical partition (LPAR), as a guest under the virtual machine operating system, and within the Virtual Image Facility (VIF).
In September 2000, IBM introduced the Integrated Facility for Linux (IFL) and the aforementioned VIF. An IFL is an IBM specialty processor dedicated to running the Linux operating system, with or without z/VM. The IFL was introduced by IBM to allow Linux operating systems and applications to run on the mainframe, freeing Linux on the mainframe users from paying the normally high cost of mainframe software licenses. An IFL is viewed as a single CPU for licensing purposes and microcode restricts IFLs to Linux workloads. IFLs are available for all IBM mainframes, as far back as the G5 series. Fujitsu and Hitachi also offer IFLs on certain models.
An IFL is not required to run Linux; Linux runs on general-purpose processors (CPs) as well. IFLs simply cost less. The initial price for an IFL was around $100,000 but IBM, in recent pricing changes, now sells an IFL for some mainframes (such as the z10 Business Class) for about $47,500. The price is about $75,000 on other larger mainframes. IBM says that approximately 4,600 IFLs were actively being used in 2008.
At the same time that IBM introduced IFLs, it also introduced a special, Linux-only, VM-like product, the S/390 Virtual Image Facility for Linux. It was aimed at IT staff previously unfamiliar with IBM mainframes. Shortly after the release of VIF, IBM found that z/VM was not difficult for IT staff to use and the S/390 VIF for Linux was discontinued in April 2002. IBM and SUSE laid the basis for Linux for the mainframe to be successful in 1999 and 2000.
Over the years, various features available on the mainframe have made their way into the Linux code base for multiple platforms, leading to significant improvements in the Linux operating system. For example, mainframe dynamic resource management capabilities have made their way into Linux for x86 platforms, and features such as the tickless timer have also made their way from the mainframe into the Linux code base.