Test Plan Charlie: 41000 Linux Servers on One Box

There was a test done many years ago by David Boyes, an engineer working out of Virginia.  The test was simply to run as many Linux servers on one IBM zSeries mainframe – and to keep adding them until something broke.

The test hit the limit at 41,400 Linux servers – and nothing ever “broke.” This project was widely reported at the time, though it seems to be forgotten now. However, the test caught my fancy. That’s a lot of Linux machines.

As was mentioned, this report was widely reported: Linux Journal had an article on 1 June titled The Penguin and the Dinosaur from Adam Thornton. That same day, Daisy Whitney authored an article, Linux on Big Iron – possibly in Datamation. Scott Courtney (the Technical Editor for Internet.com) wrote S/390: The Linux Dream Machine on 23 February and wrote It’s Official: IBM Announces Linux for the S/390 on 17 May. What really stands out? All of these articles reporting on the S/390 and on Test Plan Charlie occurred nine years ago, in 2000.

Scott Courtney followed his articles up with an interview with David Boyes in 2001.

There is one more thing about David Boyes: following Test Plan Charlie, he went on to create Sine Nomine Associates and showcased OpenSolaris running on the IBM zSeries in November of 2007 – with attendant press releases from IBM. Certainly, David is not one to sit idle – and is a figure to contend with in the IBM zSeries arena. IBM has, since the original announcement nine years ago, pushed Linux on zSeries with vigor.  One irony: Test Plan Charlie was part of a study for an IBM customer that was deciding whether to use their existing S/390 or whether to use a new Sun set up.

There is even an open source IBM mainframe emulator called Hercules, which allows the rest of us to try it out and see what happens – even though you won’t be able to run under z/VM, as that is an IBM product.

Update: there was a nice set of updates about OpenSolaris on zSeries over on DancingDinosaur: Here comes (and goes) the Sun (12 April 2009) and Slow times for OpenSolaris on System z (21 July 2009).

Update: More articles on Test Plan Charlie. In the November 2000 issue of Technical Support, Adam Thornton wrote a nice two-part article (part one and part two) on it. Adam is a major contributor to the Linux on S/390 effort and worked for David Boyes at Rice University.

A good source of information for Linux on S/390 is linuxvm.org.

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One thought on “Test Plan Charlie: 41000 Linux Servers on One Box”

  1. I cannot say for certain, but I believe I witnessed something similar at a Share conference in Seattle back in 2006. IBM had a IBM zSeries setup and had a procedure running that was continuously creating Linux guests. It was only running during the time that the one area of the conference was open, probably a few hours. But I remember they had a counter running and it was incrementing each time a new guest was created. I am certain it never reached 41,000, but it would not have needed to reach that kind of number to still be impressive. Share was and I suspect still is primarily a mainframe conference. Back then I was administering SUSE Linux on the mainframe, at that time we were running 170 plus Linux servers that were actually doing something.

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