The IBM Z ecosystem contains multiple operating systems, including IBM z/OS, z/VSE, z/TPF, and z/VM. So where does Linux fit in?
First, let's talk about the terms surrounding Linux on the s390x chip architecture found in IBM Z and LinuxONE. IBM LinuxONE is a hardware product line. You can think of it as the sister brand to the IBM Z mainframe line, with similar hardware and specifications, but only running Linux. When people talk about running Linux on the mainframe, they often used to say "zLinux" and while this is expedient it has some challenges in that it creates the impression that Linux on Z is somehow different from Linux everywhere else — and as those who know the kernel will attest, it's not. The correct or more commonly used phrases now are "Linux on Z" when referring to Linux on a mainframe, or just simply "Linux" when talking about Linux running on LinuxONE.
Linux itself was first introduced to the mainframe as a community-driven project in 1998, and then in December 1999 IBM released their first series of patches for the 2.2.13 kernel. This makes Linux a relative newcomer as far as operating systems go in the mainframe space. Over the years, Linux on Z became a staple of many organizations running alongside operating systems like IBM z/OS, z/VSE, and z/TPF, which people more frequently think of when you’re talking about mainframes. In 2015, the first LinuxONE was released, cementing Linux as an operating system that was here to stay on the platform.
The role Linux plays in this ecosystem is multi-faceted. It’s not intended to replace the others; indeed, there are updates to z/OS and z/VSE regularly, with organizations getting together at industry conferences on a regular basis to share their expertise regarding the latest features. Not only that, but a whole open source ecosystem has sprung up to take these modernization efforts further with projects like Zowe from the Open Mainframe Project. Finally, z/OS itself has an included component called UNIX System Services, which was first released back in 1998; it brings a UNIX-like environment to z/OS and is heavily used in many organizations.
What Linux brings to the ecosystem is a suite of popular software and a computing environment that’s more familiar to today’s cloud-native developers and systems administrators. It’s also not just a simple port; while Linux on Z and LinuxONE may feel like and be used in the same way as an x86 server to the user, deep in the kernel you’ll find enhanced hardware support that’s specifically designed for use with the mainframe, from accelerated cryptography support to compression and decompression, and more. Even languages that have been brought to Linux on Z, like Java and Go, have components that take advantage of hardware-driven encryption support.
With Linux on Z, the other strengths of the mainframe make them a continued staple of the tech industry. The hardware is built to enterprise-grade standards, with redundancy built into the core. The processors are some of the fastest commercially available on the market, and have built-in cryptographic co-processors, so encrypting all of your data both at rest and in flight doesn’t detract from the general computing processes on your system. And this is all done with libraries, tools, and modules that Linux users are already familiar with, from OpenSSL to IPSec, and dm_crypt in the kernel.
Organizations that run workloads on other mainframe operating systems also get the benefit of Linux on their existing IBM Z, or in a nearby LinuxONE, by having physical proximity to their data. This offers significantly faster access to data and decreases data transit costs that you may encounter in other environments — all while running the latest frameworks available for Linux.
Welcome to the world of Linux on Z and LinuxONE! If you’re a developer who doesn’t yet have access to your own Virtual Machine running on LinuxONE, check out the IBM LinuxONE Community Cloud which gives you 120 days of free access to a SUSE Linux Enterprise Server, Red Hat Enterprise Linux, or Ubuntu VM.