Facebook has started to build a data centre on the edge of the Arctic Circle in Lulea, Sweden, where it will benefit from cheap electricity and year-round free air cooling, the company announced yesterday.
The data centre will be Facebook's first in Europe, and its third worldwide. The social networking site expects to begin fitting out the first server hall by the end of next year, and will begin serving the first Facebook users from it in April or May 2013. Three other server halls in the same 28,000 square-metre building will be ready for fit-out by 2014. The site has room for two other buildings of the same size, but Facebook has no plans to begin constructing them yet, according to Tom Furlong, the company's director of site operations.
Lulea is on the edge of the Arctic Circle, and has a mean annual temperature of around 1C, with average summer highs of around 20C, allowing Facebook to save money by cooling its data centre with fresh air rather than air conditioning.
Power usage effectiveness
About two-thirds of the floor area will house servers, the rest being reserved for support functions such as an evaporative cooling system for use during particularly warm spells, Furlong said. This can also be used to humidify the air during dry weather, to reduce static electricity risks, he said.
Using free air cooling will help Facebook increase a key measure of data centre efficiency, its PUE (power usage effectiveness). PUE is calculated as the total power consumption of the data centre, including cooling and lighting systems, divided by the power consumption of IT systems. The less power wasted on ancillary functions such as cooling and lighting, the more energy-efficient the data centre becomes.
Average PUEs for major data centres typically lie between 1.6 and 1.99, according to a survey published by the Uptime Institute in May. Capgemini said last December that its Merlin data centre in the UK had a factory-tested PUE of 1.1.
Facebook is hoping its Lulea data centre will have a PUE similar to that of its existing one in Prineville, Oregon, which has a PUE of 1.07, said Furlong.
The servers there will run primarily on hydroelectric power from the nearby Lule river, Facebook said. Lulea has the cheapest electricity in Europe, according to the city's business development agency.
"This not the first data centre in Lulea, but it is the biggest," said Matz Engman, CEO of the agency. Sweden's customs authority already has three smaller data centres in the city to track imports and exports, he said.
Lulea is now hoping to make a name for itself as a cool place to build a network node. With two neighboring cities, it is branding itself as the "Node Pole," Engman said.
Before selecting Sweden to host its first European data centre, Facebook considered a number of other countries. Forty sites were considered, and the company visited a shortlist of eight. In addition to Lulea, one other site met all Facebook's criteria, said Furlong.
Facebook has developed its own power-efficient servers and power supplies for centres, publishing technical specifications and CAD files for them through the Open Compute Project.
In particular, Facebook uses a highly efficient electricity system with battery backup close to each rack, said Furlong.