See
http://en.wikipedia.org/wiki/Veteran...y_Architecture and
http://www1.va.gov/cprsdemo/docs/Vis...nl_Article.pdf . It is common knowledge that Google's search engine is probably the app running on the most servers as a single system, and some of the government's supercomputer apps like their weather forecasting and nuclear simulation programs may run on the largest multiprocessor systems, and of course there is the (black) NSA software they use to monitor all our communications, but I wonder what is the largest app in public production use in terms of lines of code or bytes of source code. I would be interested in any information anyone might have on that. Might provide a good argument in our evangelizing.
The VA mainly use Compaq Alpha clusters of 1-12 processors according to the article, but one would expect them to migrate to Linux platforms in the normal course. As a VA patient I have seen the system in use and it seems to be well done. Since it is open source one might expect it to be adopted widely and mainly on Linux platforms.