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How a data centre works

A bluffer’s guide to the complex world of data hosting − from power stations to blade servers

1. Power generating station
Could be coal, gas, nuclear or renewable. A medium-sized data centre requires 10 megawatts (MW) of power; larger ones need 100MW or more. That’s the equivalent of one tenth the output of a generating station like Sizewell B.

2. Power distribution network
Power is transmitted from the generating station – usually on a distant coast or river far from the data centre – typically located in London, Manchester or other major cities around the UK, close to where telecommunications fibre cables provides connectivity to the internet. Up to 6 per cent of the generated power is lost over the long distances involved.

3. Substation
The National Grid operates at 400,000 volts. Big substations bring the voltage down before connecting to the datacentre’s own substation where it is converted into the 440 volts and 240 volts needed to operate the equipment inside the data centre.

4. Data centre
Often the size of many football pitches these giant data factories live in anonymous industrial buildings hidden away on industrial estates or in ordinarylooking office blocks in cities.

5. Standby generator
Often rated at half a megawatt each, the generators keep the data centre alive if both its primary power sources fail.

6. UPS (Uninterruptible Power Supplies)
Another system inside the data centre called UPS (uninterruptible power supplies) can keep the facility running on battery power for around ten minutes, long enough to get the generators running smoothly and ready to take over.

7. Chillers
Most of the energy that goes into running a data centre ends up as heat. Massive industrial chillers, or refrigeration units, create very cold water which is pumped inside the data centre to equally massive Cracs (computer room air conditioning units) which flood the data centre with cold air to be sucked through the servers to keep the chips cool.

8. A 19in rack
Where the servers and other electronic equipment are located. The mounting width of all electronic equipment is a standard 19 inches and equipment height is
measured in terms of its “U” height. One “U” is about 1.75 inches and is the height of a pizza box server.

9. Pizza box server
The data centre workhorse – an industrial version of a desktop computer but built to a much higher specification. Contains processor(s), hard disks, two power supplies (so that one can fail) and lots of RAM.

10. Blade server
The new darlings of the data centre industry, these are far smaller than the pizza box server. The size reduction is achieved by stripping out elements like the power supplies and mounting them in a chassis or shelf into which 16 or so smaller server cards or blades are plugged. Blade servers squash so much processing power into a small space that one chassis can consume 16 kilowatts.

New Statesman
Going Digital: Where is our Data? An introduction to data centres


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