Way back, SUSE had something like 90% of the Linux marketshare on IBM mainframes. IBM's initial Linux work on the platform was done in Germany (Bohlingen I believe.) That eroded over time as Linux on the mainframe went more mainstream and Red Hat added similar mainframe support features to what SUSE had.

Bohlingen? I have never heard about such an IBM location.

Maybe you meant Böblingen. That used to be a big research and development site since the days of punched cards until its shutdown was announced 2 years ago. They did a lot of zSystem stuff, no idea whether anything with SUSE.

Disclaimer: I was a trainee at another IBM research site long before Linux was invented. So I cannot reveal any internals about the topic.

I'm sure you're right which is why I couldn't confirm it on Google.

Example: https://newsroom.ibm.com/Bringing-Linux-to-IBM-Z This is very politically partner-agnostic but a lot of the work was specifically around SUSE in the early days.

>This is very politically partner-agnostic

Not really. Redhat and SUSE get named explicitly.

Edit: Ubuntu, too.

What I meant was that it was really all about SUSE originally. Red Hat came later and AFAIK Ubuntu has never really been a material presence on IBM mainframes. No one else has ever mattered with respect to commercial Linux distributions that would run on a mainframe.

I still see many banks using it. I think in the future they will end up using Redhat, but until now, I still didn't see it happening.