This month, Planet Mainframe celebrates influential mainframers nominated by the community.
Today, we spotlight a z/OS performance powerhouse.
John Baker
Principal Consultant, z Performance, IBM
Toronto, Ontario, Canada
Connect with John on:
View the entire 2025 Influential Mainframers group here.
For more than thirty years, John Baker has been a quiet force behind some of the mainframe world’s sharpest minds. Known as the go-to for z/OS questions—especially performance-related—his reputation is built on deep technical mastery, insatiable curiosity, and calm under pressure.
“John has been my mentor throughout the years,” shared one nominator. “He teaches, advises, and leads empathetically, which is extremely rare in our field.” Another added, “He doesn’t forget anything he’s learned in his 30-year career—and generously shares every bit of it.”
John began his mainframe journey as a customer, designing and implementing large-scale initiatives like WLM Goal Mode, GDPS/Data Mirroring, and major data center mergers. He focuses on system and application performance, and his expertise has benefited some of the world’s largest banks and data centers.
He joined IBM as part of the IntelliMagic acquisition and continues to lead through education and community engagement. In 2024 alone, John spoke at numerous SHARE sessions, hosted roundtable discussions at GSE UK, and led multiple zAcademy webinars—an initiative launched during the pandemic to help the broader mainframe community sharpen their skills.
Along with speaking and writing, John frequently appears on podcasts, webinars, technical blogs, and community forums. His presentations are known for making dense topics approachable and actionable.
He is involved with the MVS Performance Project at SHARE, and previously served on the Board of Directors for the Computer Measurement Group (CMG). When not immersed in z/OS, John enjoys pool, motorcycles, his dog, a good glass of old port, and the occasional spirited political debate. He lives with his family near Toronto, Canada.
Influential Mainframer
Mainframe technology continues to evolve because of the dedicated professionals, educators, mentors, and innovators who drive it forward. We’re shining a spotlight on the individuals who are making waves—whether they’re advancing technology, mentoring new talent, sharing knowledge, championing modernization, or quietly keeping mission-critical systems running every day. These are the people shaping the future of mainframe. They come from all backgrounds and experience levels, but they all have one thing in common: they’re making a difference.
Check back daily as we reveal a new honoree. Read their stories, celebrate their impact, and be inspired.
Follow @Planet Mainframe and follow #pmfinfluentialmainframers to congratulate this year’s honorees, share your favorite stories, and spread the word.