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.
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.
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.
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.
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.