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Dell urges datacentre managers to turn up the heat

IT giant claims many server farms are wasting energy by keeping the air temperature far lower than the equipment requires

Published: James Murray, BusinessGreen 28 Feb 2008

Firms are wasting millions of pounds on their energy bills, emitting vast amounts of carbon dioxide and could even be undermining the reliability of their IT equipment as a result of their desire to keep the air in their server farms significantly colder than is technically required.

That is the view of Albert Esser, vice president of datacentre infrastructure at IT hardware giant Dell, who argued that some datacentres could cut their energy bills by up to five per cent with no adverse impact on their servers' reliability by simply increasing the temperature of their server farms by five degrees.

"A culture has developed among datacentre managers that the colder it is the better," he said. "But as long as you stay within the equipment manufacturers' specifications you can often keep the ambient temperature higher – cutting the energy bills and saving substantial amounts of money."

He added that firms could reduce cooling demands further by optimising the layout of their datacentres. "The reason a typical datacentre is so cold is because they have to cool a couple of racks that run very hot," he said. "If they address those few racks and perhaps spread out the servers more, they can raise the ambient temperature."

According to Dell, air being pumped into a datacentre can typically be as cold as 19 degrees centigrade, despite the fact that systems will remain reliable as long as the temperature is lower than 25 degrees centigrade.

Esser pointed to a recent datacentre rollout that Dell contributed to, where the temperature was kept at 19 degrees, resulting in a Power Usage Effectiveness (PUE) ratio for the datacentre of 1.8. This means that for every watt used to power the servers, 1.8 entered the datacentres. However, when the temperature was raised to 23 degrees the energy efficiency of the facility improved significantly, resulting in a PUE of 1.3.

He also warned that far from improving the reliability of their servers, some people were jeopardising it by keeping the temperature in their datacentres too cold. He said that where managers cut air temperature to cope with server hot spots the increase in relative humidity levels could lead to water condensation that results in corrosion of components.

Andy Lawrence, research director for eco-efficient IT at analyst firm The 451 Group, said there was a growing consensus amongst datacentre operators and equipment suppliers that server farms are being run colder than they need to be.

He said that Google has recently presented papers that shows that disk drives do not fail more often at temperatures of 75 to 100 degrees Fahrenheit, while BT is on record as saying "all modern systems will operate effectively and reliably between five and 40 degrees Celsius".

However, Lawrence warned that IT managers should carry out thorough assessments of their datacentre before turning up the temperature. "It's simplistic to say that datacentre operators should just go in and turn the thermostat up a few points," he said. "Especially because heavily laden, mission critical servers running consolidated workloads can get very hot very quickly if the cooling isn't working optimally."

Julian King, chief executive of datacentre design and development firm Galileo Connect, agreed that it was "entirely feasible" for many datacentres to cut their energy bills by operating at a higher temperature. But he warned that many IT managers would be reluctant to let the temperature get as high as the specifications recommended by server manufacturers of between 23 and 25 degrees.

"The problem is that if you have a cooling system failure and the datacentre is already pretty warm, you end up with a critical issue far more quickly," he said.