20 years of Linux on Big Iron

Decades ago, people predicted that IBM and its mainframes would soon be history. But then IBM and Red Hat brought Linux to the mainframe and things would never be the same again.
Written by Steven Vaughan-Nichols, Senior Contributing Editor

Let's take the way-back machine to March 1991. Back then Stewart Alsop, venture capitalist and one-time editor-in-chief of InfoWorld, predicted "the last mainframe will be unplugged on March 15, 1996." In IBM's last quarter, IBM Z mainframe led IBM's systems revenue to $1.9 billion, a gain of 6% over the last quarter. Oh well, you can't get them all right. 

So, what happened? Linux happened.

At the time, this seemed a very unlikely marriage of software and hardware. Linux was the open-source software darling and the IBM mainframe was the proprietary hardware king. IBM leadership could see, long before other major companies would, that Linux was the future of operating systems.

So in February 1999, IBM announced it would work with Red Hat to support Linux. By May 2000, Linux moved from being an experiment on mainframes to being a fully supported option. And in 2001, IBM announced it was spending a billion bucks that year on Linux. That only sounds like a huge bet. As Bill Zeitler, an IBM's senior vice president, later explained, "We've recouped most of it in the first year in sales of software and systems."

It wasn't an easy sell at first. Dan Frye a member of the original IBM Linux strategy team, remembered, "Our initial strategy team included experts from IBM's x86 Intel-based server, IBM Software, and technical services businesses. The IBM s/390 -- the precursor to IBM Z mainframes -- was not included because enterprise IT existed in a different universe." So, while IBM decided to put its money on Linux, the mainframe world kept on its proprietary way.

20 Years of Linux on the IBM Mainframe timeline

20 Years of Linux on the IBM Mainframe. 


But, at the same time, some skunkworks programmers at IBM Böblingen in Germany began porting Linux to the IBM mainframe "just for fun." It only took them a weekend -- I repeat, a weekend -- to get basic Linux running. 

By the spring of 1999. Frye recalls, "Enterprise Systems Group General Manager William Zeitler had enough information for a final chart of his presentation to then-CEO Lou Gerstner: 'We also have Linux on s/390,' Zeitler said."

Gerstner was not impressed at first. In fact, "'That's the stupidest idea I've ever heard,' said Gerstner, who then paused for reflection and added 'Or maybe not?'"

After much careful thought about whether to officially port Linux to s/390 and what such a move would do to its existing mainframe business, IBM decided to take the IBM mainframe Linux plunge. And so it was that IBM launched four Linux distros -- Caldera, Red Hat, SUSE, and Turbolinux -- on S/390 in May 2000.

Irving Wladawsky-Berger, then IBM's Vice President of Technology and Strategy, explained to the skeptical stockholders that "if Linux were just another operating system, we wouldn't be all that high on it. But that's what's so interesting. Linux is an operating system, but it's also radically different from anything that has come before it. It changes the way software is created and delivered."

He was 100% correct.

It was the smartest move IBM made in the 21st century. 

IBM would end up acquiring Red Hat in late 2018. Today, the two work hand-in-hand not just on Linux but the hybrid cloud, which runs above it. 

SUSE remains a strong IBM Linux partner to this day. Indeed, SUSE maintains that more businesses choose SUSE Linux Enterprise Server (SLES) for IBM Z and LinuxONE than any other Linux for running workloads on IBM mainframes. Alan Clark, a SUSE CTO, commented, 

Despite the tendency of some to dismiss mature technologies, neither Linux nor the mainframe could in any way be considered "outmoded" or "antique." The issue isn't age. It's quality, reliability, security, and an ongoing ability to innovate and adapt to change. As countless commoditization cycles within the IT industry have written lesser technologies into the history books, Linux on the mainframe is enabling businesses to write the next chapter in their story of digital transformation.

Clark's right. 

Nor are Red Hat and SUSE the only Linux companies supporting the mainframe today. While Caldera and TurboLinux are history, today Canonical's Ubuntu Linux's parent company is a major mainframe Linux provider

Today, the IBM mainframe and Linux are stronger than ever. Ross Mauri, IBM Z's General Manager, said, "What's most exciting to me are the new Linux workloads we're seeing on the platform. I've talked with more healthcare and fintech startups in emerging industries like digital asset custody in the past three years than previously in my entire 40-plus IBM career."

So, far from dying, Linux gave the mainframe new life. Instead of simply supporting old big iron jobs, the pairing of IBM and Z mainframes are finding new tasks for this powerful combination. 

PCs may come and go, operating systems rise and fall, but Linux and the mainframe are forever.

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