Inside Cern's atom-smasher number-cruncher

In the basement of the computer centre are tape-storage machines, which record the LHC data before it is processed. The data is then partly processed by the blade servers upstairs, and partly through the grid. "The tape is not backup", said Jouanigot, "it's a source of data".

Five-petabyte storage disks act as a buffer for the data while it is copied from tape onto disk. From there it is passed to processors to start data analysis. Four robots, each containing 20,000 tapes, initially store the LHC data.