@hessies,
You can read, or take a guided tour, see more Pics, Get all the software/Hardware details
HERE!
Linux FARM
I don't remember all the details, as I did ask the same question when I visite. I believe the answer was someting like this:
1. Being a National Lab, and offering their research, servers, applications, computing resources, to the entire world's scientific community; They went with an OS that is as stable as UNIX and "free" to scientist and citizens around the world.
2. I believe (trying to find the article) that at the time the head of the RHIC computing facility was heavily involved in developing Red Hat Linux.
So I think the equation went something like this:
"Cost Effectiveness" + "Cheap Licensing" + "Power" + "Stability" + "Open-Source" + "Customization" + "Availibilty to the world's scientific community" + "Nerds Love Linux" = Linux Wall
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Welcome to the RACF Computing Facility at the Brookhaven National Laboratory (BNL).
The facility provides computing services for the experiments at the Relativistic Heavy Ion Collider (RHIC) at BNL, the US-based collaborators in the ATLAS experiment at the Large Hadron Collider at CERN, and the collaborators in the Large Synoptic Survey Telescope project.
The major components of the RACF are the 14 TFLOPS processing farm (currently with over 4000 processors), the distributed and centralized disk storage farm (1 PB of on-line disk storage), the robotic tape storage silos (7 PB of storage) and the grid computing software infrastructure. The hardware is a combination of commodity-based processing servers, enterprise-class UNIX servers and highly-specialized mass storage systems connected together by a high-speed network infrastructure.
Since its establishment in the 1990's, the RACF has grown to its current level of 36 staff members. The combined RACF staff operates and manages, year-round, a heterogeneous, large-scale multi-purpose facility, serving a worldwide community of about 2,400 (and growing) users, while continuously innovating and addressing the ever-changing computing requirements of our user base.
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Note:
The BNL Physics/Computer Department is very generous in sharing with anyone who shows an interest. And I mean that literally. These people will go to great lengths to explain anything and everything you wish to know. They don't talk down to you, and have a way of bringing things to whatever level of education you have.
On my visit with the Computer Science Club (We weren't Physics Majors), most of engineers even went to lunch with us (on their time) to talk about video games. A few came to our Club Meeting on campus a month later, to see the projects we were working on
and to get free pizza! 
BTW: They liked DBC!!!!
In many ways they are a lot like us here, they are truly passionate about what they do, and are willing to offer help to anyone who wants to learn.
