The Vader-black machines, one built by StorageTek, a subsidiary of Sun Microsystems, the other by IBM, are housed in square, meshed-in casings the size of small shipping containers. From within them comes a continuous clacking noise like the rattling of steel polyhedral dice on a giant's Dungeons & Dragons table. I pressed my face against the mesh and peered in fascination at the robot arms zipping back and forth with tiny, precise movements, loading and unloading 500-GB tapes with the serene grace of Shaolin monks. Did I say tape is tetchy? I take it back. Tape is beautiful.
At each data centre I asked the sysadmins for their worst fears. Universally, the answer was heat. Data centres are laid out in alternating cool and hot aisles, the cool looking at the front of the racks, the hot at the back. At CERN, they actually glass over the cool aisles to lower the cooling requirements, turning them into thrumming walk-in fridges lined with millions of tiny, twinkling lights.