Cory Doctorow has written an article for Nature about petsacale data centers that provides a look inside three European facilities: The Wellcome Trust Sanger Institute in Cambridgeshire in the UK, the XS4ALL data center in Amsterdam that hosts a mirror of the Internet Archive, and the computing center at CERN near Geneva that supports the Lareg Hadron Collider (which is in the news today).
An excerpt: "This was one of the coolest writing assignments I've ever been on, pure sysadmin porn. It was worth doing just to see the the giant, Vader-cube tape-robots at CERN (pictured at left). At this scale, memory has costs. It costs money — 168 million Swiss francs (US$150 million) for data management at the new Large Hadron Collider (LHC) at CERN, the European particle-physics lab near Geneva. And it also has costs that are more physical. Every watt that you put into retrieving data and calculating with them comes out in heat, whether it be on a desktop or in a data centre; in the United States, the energy used by computers has more than doubled since 2000. Once you're conducting petacalculations on petabytes, you're into petaheat territory. Two floors of the Sanger data centre are devoted to cooling. The top one houses the current cooling system. The one below sits waiting for the day that the centre needs to double its cooling capacity. Both are sheathed in dramatic blue glass; the scientists call the building the Ice Cube.