http://www.beowulf.org/ ) is way to produce a high power parallel computing system by networking together a number of low cost computers with a free to use operating system, based on Unix.
This was an extremely attractive idea to university departments who wanted a huge amount of computing power on a limited budget. There are many stories of clusters being made from systems rescued from skips, and legend has it that in one London university students would swarm over the building late at night, rebooting every available PC from a floppy disk into the cluster, and then rebooting them back before anybody else arrived next morning. It would be nice to suggest that this was for Astrophysics or sub-atomic particle research, but in fact it was to run a Dungeons and Dragons programme.
An article in The Register tells how Boise University PhD candidate Joshua Kiepert built a 32-way Beowulf cluster from Raspberry Pis.
The RPis were stacked in groups of eight with enough room between them for a reasonable amount of air flow and component clearance he writes. “This configuration suited our needs for power distribution very well since it allowed for a power line to be passed vertically along each stack."
Joshua is extremely happy with the results of his cluster and has written his work up as a PDF file, and if you have any interest in doing something similar then I can recommend reading it in detail. The cost of this? around £1500, or the cost of a decent high powered 4 core system.
[Full story from The Register]