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Upgrading what might be the world's oldest running Linux install

If you use Putty, there's a good chance you've visited Chiark

There are some complexities involved in upgrading what the Reg FOSS desk suspects may be the world's oldest running Linux installation: an OS install dating back to 1993.

The machine called chiark.greenend.org.uk appears to be a relatively ordinary webserver, hosting a bunch of home pages, a few mailing lists, usenet groups and things. People with no links to Cambridge University may have encountered it only if they downloaded the PuTTY SSH client for Windows from the author's own site.

What's remarkable about Chiark is that it was originally installed with Debian Linux 0.93R5 in 1993, and the same installation of the OS is now running Debian 11 "Bullseye", the x86-64 version, freshly upgraded from an x86-32 installation of Debian 8 "Jessie".

That's why its administrator, Ian Jackson, described the process as a "skip-skip-cross-up-grade" – "skip" twice, because he skipped both Debian 9 and Debian 10 – and "cross" because he also moved the system from 32-bit to 64-bit in the process.

Jackson is highly qualified to perform such a complex upgrade: as well as being a former Debian project lead, he also wrote Debian's underlying package-management tool dpkg. Jackson stewarded the release of Debian 2.0, the first multi-architecture version of the distribution, and the first to use libc6. He resigned from the Debian Technical Committee in 2014, after his proposal that Debian packages should remain init-system agnostic was defeated.

For details of the upgrade, we refer you to Jackson's blog post. We found it notable that it was all done remotely, without a site visit, and that chiark runs LVM on top of RAID on top of LVM – a decidedly non-trivial disk configuration. The most problematic programs were Apache 2, the Mailman mailing-list tool and Exim MTA, the INN news server, and moving from a Python 2-based release to a Python 3-based one.

The names "Chiark" and "Diziet" are from the science fiction of the late Scottish author Iain M Banks, who died from cancer in 2013. The former is from the novel the Player of Games and the latter first appeared in the anthology the State of the Art – both relatively recent when the machine was first commissioned. This was the same year that Intel released the first Pentium processor.

Jackson describes its existing installation as "at the very high end of the installation complexity, and customisation, scale".

Going to such lengths to preserve this and keep it running as-is would be way beyond the skill level of all but a few people. However, Chiark is well on its way to being a significant cultural artifact in its own right, as well as demonstrating the remarkable flexibility of its operating system.

This must surely be one of the paramount examples of a "server as a pet", as contrasted with the devops style of systems management: "servers as cattle". We suspect that many 21st century systems administrators will be scornful of this quite remarkable achievement. This, we submit, is a mistake: it is complex, difficult edge cases such as this that expose some of the most difficult issues in software design and implementation.

Although The Reg delights in stories of elderly hardware that is still in production use, this is something different: relatively modern hardware, running a nearly 30-year-old OS install that's now pretty much current. If you know of anything older, we'd love to hear about it. ®

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