Scientific Linux

» see scientificlinux.org as it lived, on the wayback machine

~ the obituary ~

Fermilab had a problem that money does not cleanly solve. A particle physics experiment runs for fifteen or twenty years and generates data that has to stay readable for longer than that. Its computing is spread across thousands of machines in dozens of institutions in a dozen countries, most of which have their own procurement rules. What the lab wanted was the stability of Red Hat Enterprise Linux, which is built for exactly that kind of decade-scale commitment, without a per-machine invoice attached to it.

Red Hat publishes its source. So Fermilab took the source, stripped the trademarks, rebuilt it, and released the result on 10 May 2004 as Scientific Linux. Connie Sieh, a computer specialist at the lab, drove the first prototypes and the initial release. The project grew out of the lab's earlier in-house distribution and quickly picked up collaborators: CERN maintained its own variant, and DESY in Hamburg and ETH Zurich were involved in the broader effort.

What it became was infrastructure nobody outside the field ever needed to think about. When the Large Hadron Collider began producing collisions, the grid that processed the output was running Scientific Linux or CERN's build of it across sites on several continents. It spread sideways from there into medical physics and into university departments that wanted a free enterprise-grade system without a support contract.

The end came in two stages, several years apart. In April 2019 Fermilab announced that there would be no Scientific Linux 8 and that the lab would move to CentOS. Feature development was finished. The existing releases were to be maintained to the end of their own life cycles, and the last of them, Scientific Linux 7, reached end of life on 30 June 2024.

~ the case file ~

~ the rebuild economy ~

For about fifteen years the Red Hat clone was a stable and slightly strange corner of the software world. Red Hat's business was support rather than bits, and it published the source it was obliged to publish, which meant anyone willing to do the compile work could ship a functionally identical system for free. CentOS was the general-purpose answer to this. Scientific Linux was the specialized one, carrying extra packages the physics community actually needed and a release cadence tuned to experiments rather than to enterprise refresh cycles.

The duplication was always slightly awkward, and Fermilab said as much in 2019. Two groups were maintaining near-identical rebuilds of the same upstream for overlapping audiences. One of the two was a national laboratory whose actual job is physics.

~ the part that did not age well ~

Fermilab moved to CentOS in 2019. In December 2020, roughly eighteen months later, Red Hat announced that CentOS Linux as everyone understood it was ending, to be replaced by CentOS Stream, which sits upstream of Red Hat Enterprise Linux rather than downstream of it. The stable free rebuild that Scientific Linux had been retired in favor of was itself discontinued before Scientific Linux had finished dying.

The physics community absorbed this and moved again, mostly to AlmaLinux and Rocky Linux, the community rebuilds that appeared specifically in response to the CentOS decision. CERN and Fermilab went to AlmaLinux. The requirement never changed across any of these moves. What the labs wanted in 2004 and what they want now is the same thing: a long-lived free rebuild of Red Hat that somebody else maintains.

~ the site that outlived the system ~

scientificlinux.org still answers. The front page says the distribution reached end of life on 30 June 2024, and keeps the download links and the documentation for SL3 through SL7 sitting where they were. There is no farewell letter and no gratitude paragraph, which fits an operating system released by a government physics laboratory.

This is the one category on this site where my own work overlaps. Rebuilding Red Hat because the license cost collapses the moment you count the servers is a familiar calculation to anyone who has run Linux infrastructure in Turkey, and the free rebuilds are the reason a lot of that infrastructure exists at all. The specific world Scientific Linux was built for, grid computing for collider data, is not one I have been anywhere near.

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