IBM is introducing two mainframe servers that run only on the open-source Linux operating system. Here are some articles on it:
http://www.bloomberg.com/news/articles/2015-08-17/ibm-introduces-two-open-source-only-mainframes-in-hardware-push
http://techcrunch.com/2015/08/16/linux-foundation-launches-open-mainframe-project/
http://techcrunch.com/2015/08/16/ibm-teams-with-canonical-on-linux-mainframe/
Regards,
Roger Lacroix
Capitalware Inc.