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The megacentre has a power usage effectiveness (PUE) rating of 1.148, which includes the power cost of the separate mini-datacentre used to store the tapes. The main processing hall itself has a PUE of 1.127.
Power usage effectiveness expresses the ratio between the total facility power and the power used for the IT equipment itself. The closer a PUE rating gets to one, the greater proportion of a facility's power is being expended on its IT equipment and the lower on the supporting infrastructure.
The PUE of 1.127 was achieved through the separation, cooling and recirculation of air within the datacentre, using a combination of adiabatic cooling, outside air and filtering to cool the air without spending much on power. The facility can be free-cooled for all but 100 hours per year.
Each set of racks face onto one another, with the exhaust vents facing into a central corridor, sealed off from the rest of the datacentre. Inside the corridor, the hot air rises into a ceiling aisle and passes through to the cooling systems.
Photo credit: Jack Clark
Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.