iTnews asks: How hot should you run your data centre?

With power bills set to blow through the roof, data centre managers are faced with a tough dilemma.

Raising the ambient temperature within their computer rooms can cut down air conditioning costs and open up greater windows of time for 'free cooling' techniques (ie using outside air to cool the room), but servers and other computing equipment are known to suffer performance issues outside of the range of temperatures recommended by the hardware vendors.

Data centre operators also face some uncertainty as to how high they can push temperatures before hardware vendors void warranty or service obligations.

This week, iTnews asked the major server vendors and some data centre operators about where to draw the line on how warm to allow your data centre to run.

Data centre metrics

Data centre managers have two metrics to rely on when choosing how warm to run a computer room - the advice of standards bodies such as ASHRAE (The American Society for Heating, Refrigeration and Air Conditioning) and the recommended operating range noted in the specifications of their box, provided by the vendor.

In terms of standards, ASHRAE's TC9.9 technical committee, which lists 'Environmental guidelines for datacom equipment", is best regarded.

In 2008, ASHRAE's TC9.9 recognised that increasing the temperature of ambient air within the data centre would provide efficiency gains in the cooling system of data centres. The technical committee increases the envelope (range) of recommended temperatures from 20-25 degrees Celsius (recommended in 2004) to 18 to 27 degrees.

"It is recognised that we can save a lot of energy if we operate these machines at higher temperatures by expanding the temperature range," said David Yip, ANZ Leader for IBM site and facilities services.

Every since the ASHRAE shift, Yip said, data centres that had insisted on operating at around 21 and 22 degrees "can feel comfortable raising their temperature."

But Yip concedes that data centre managers are under pressure to reduce air conditioning costs further still. As servers get ever more powerful and clients seek more density from their racks, data centre managers will soon enough be tempted to raise the mercury further yet.

Canberra Data Centre, a modular facility in the nation's capital, began its operations at 21.5 degrees last year but is already pushing 23.5 degrees, using techniques such as in-row cooling, hot aisle containment and free cooling to manage the heat dissipated from computing equipment.

"Every degree you go up makes a huge difference to free air cooling capability and overall efficiency of data centre," said Greg Boorer, managing director of the facility.

But shoot too high, he said, and the performance of the machines may be adversely affected.

Recommended operating range

The second metric data centre managers rely on is the recommended operating range of temperatures supplied by server, storage and switch vendors.

iTnews asked HP, Dell, Sun/Oracle, Cisco and IBM to each provide an operating range for a standard x86-based server.

Their responses were identical - a recommended operating range of between 10 degrees and 35 degrees - provided that the server sits in a data centre at sea level (for the Dell PowerEdge R710, the IBM x-Series 3850M2, the Cisco Unified Computing System and the HP ProLiant DL380G6 - Sun/Oracle was unable to provide any metrics).

By and large, server vendors recommend reducing this limit by one degree Celsius for every 300 metres above sea level (fans within the servers have to work harder at higher altitudes due to lower atmospheric pressure).

How high to push?

As one IT manager pointed out at a recent data centre summit in Sydney, the operating ranges supplied by the vendors are all well and good, but what are the implications of exceeding them?

Would a vendor still honour its warranty or services obligations?

Boorer believes the matter is cut and dried.

"Fall outside outside of the [vendor's] recommended range and you do void the warranty," he said. "You're in warranty strife."

Andrew Connolly, data centre solutions architect at Server Racks Australia also said he has "never found an issue with warranty" because he has always kept the exhaust airspace below the vendor's maximum operating temperatures.

"But I do know of some Government customers working at remote sites that have exceeded these maximums by ten and 15 degrees," Connolly said. "They are in environments where they swap out equipment so frequently, they can allow equipment to run at nearly 60 degrees."

A grey area

Among the server vendors, only HP was transparent enough to state for the record whether it would honour warranty on a server operated outside of the recommended temperature range.

"Warranty would be voided if operated outside of our specifications," HP told iTnews in a statement.

For the rest of the industry, it's a bit of a grey area.

iTnews understands that Sun (now Oracle) deals with such issues on a case by case basis, as does Cisco.

Dell's stated policy on server hardware includes some exceptions to service and support - in which the vendor says it won't support failures caused by "fluctuation or electric power, air conditioning, humidity control or other environmental conditions" -  which doesn't inspire a great deal of confidence.

A spokesman for Cisco, meanwhile, tried to play down the issue.

"It's been our experience that this warranty is not a critical issue for most customers for two reasons - one, the hardware shuts down long before it reaches a concerning high temperature and two, end-users are typically so extremely conservative that this is not an issue in practice."

(Perhaps Cisco Systems might want to visit some data centre sites operated by the West Australian Government - where auditors have found some rooms completely devoid of air conditioning!).

Whilst IBM also won't say whether it would honour a warranty on a server operated above 35 degrees Celsius, Yip predicted the issue will raise its head over time as power costs escalate.

"We can safely say all of our servers will operate reliably up to that (35 degree) level," he said. "But research and testing shows that reliability can decrease due to heat related issues - if you're running it in 40 or 50 degrees, it won't be good for the electronics.

"The rules [around warranties] may not yet be clearly defined," he said. "This is an evolving area. It's never been looked at closely until recent years, until power costs started rising and everyone started looking for ways to save on costs.

"I do expect people testing the limits will become more prevalent," he concluded. "All of this highlights a rapid evolving industry."

How warm do you run your data centre? Have you ever had any problems with warranty? Comment below.