CERN is moving more than 2,200 industrial computers and embedded systems that run its accelerator complex from the Red Hat world to Debian 13 “Trixie,” with the switch due to finish by the end of the year.
Engineers Federico Vaga and Nikos Tsipinakis explained the decision at MiniDebConf in Winterthur, Switzerland, over the weekend, and Phoronix reported it Wednesday. It is a notable change for an institution that co-maintained the RHEL-derived Scientific Linux, used it for about a decade and then moved to CentOS in 2015.
The scope is narrower than some early headlines suggested. CERN clarified to Phoronix that the migration covers the industrial accelerator-control computers, while data centers and experimental computing stay on RHEL and AlmaLinux. Those control machines sit close to the equipment across a site of roughly 43 square kilometers and connect to about 17,000 devices, Linuxiac reported.
A CPU baseline CERN’s hardware couldn’t meet
The engineers called the “-march=x86-64-v2” compiler default “the straw that broke the camel’s back,” describing it as “forced obsolescence” for older hardware. Red Hat builds RHEL for a minimum CPU generation, and RHEL 9’s cutoff already excludes CERN’s oldest boards, which use chips such as Intel’s Core 2 Duo and make up about 47% of the fleet. RHEL 10 raises the floor again and leaves out Ivy Bridge-era boards, another 17%, It’s FOSS reported.
A risk analysis in the second quarter of 2023 priced the alternative. Staying on the Red Hat path would have cost roughly 5.4 million Swiss francs, with about 11 hardware boards redesigned, two electronic engineers, two software engineers and two technicians hired, and racks reorganized and rewired. Even assuming bug-free replacements, CERN put the chance of success at an optimistic 20%. The accelerator infrastructure also had to be ready by the fourth quarter of 2026. CERN had considered CentOS Stream as the more natural route, but the same compiler baseline applied there.
The Debian plan
Plan A keeps development on Debian 12 “Bookworm” through 2026, deploys Trixie as the long-term release from 2026 to 2030, then moves to Debian 15. Plan B stays on Trixie under Freexian’s extended long-term support until 2033. Because both depend on Debian’s LTS and ELTS programs, CERN has started sponsoring Freexian.
The move is more than a reinstall. The old boot setup relied on NFS and tftpd and dates to around 2005. The new design splits the bootloader, kernel, initramfs and userspace into separate pieces and rebuilds delivery around Kubernetes, with a controller that redeploys automatically when a machine drifts from its intended configuration. The team also flagged gaps in Debian’s official tooling for automated package building and publishing, and tools that can’t handle multiple versions of the same package.
The release choice has to follow the accelerator’s run schedule of operating periods, technical stops and long shutdowns. As the team put it, the point is to avoid having to “hotpatch a live particle accelerator.”
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