Google's cluster

[Tom A Krewson]

Does anyone know what software/hardware/interconnect they are using on the
linux cluster running at the Google search engine company? In their help
wanted adds they say that have a linux cluster with more than 10,000
servers. This would make it one the largest linux clusters in the world
but I never see their cluster in any of the top 500 cluster lists.

Thanks for any help.
Tom