April 12, 2002 -- If you build it, can you cool it?
That's the question facing data center operators weighing new high-density server technologies, as a rapid rise in "hot spots" is focusing attention on the efficient use of power and space.
The trend has makers of cooling equipment rethinking traditional approaches and developing new products, some of which use liquid coolants.
"The importance of the cooling capacity of a data center has been overlooked," said Andrew Schroepfer, president of Tier 1 Research.
The primary challenge is the uneven distribution of heat inside the data center.
"We all make cold air really well," said Tony Evans of American Power Conversion (APC). "It's getting it where it needs to be that's our problem."
Air flow through data centers is often ineffective, Evans said, moving vertically through the space while equipment requires a horizontal flow. Such inefficiencies are a greater concern now that profitability has replaced speed to market as the industry's prime directive.
Customer installations vary widely in the amount of heat their equipment generates. New ultra-thin "blade" servers allow service providers to pack as many as 300 server appliances into a single 19-inch wide rack.
"Virtually every customer we talk to has pockets of high density (power usage), and the densities are going up," said Evans.
Don Baer, vice president of OEM products at Liebert Corp., agreed.
"At present, your sites are probably at 50 to 75 watts (electrical usage) per square foot," said Baer. "If those trends continue, in the next 3 to 5 years I think we could see 150 watts per square foot."
In fact, Liebert anticipates even higher loads than that, projecting that "400 watts per square foot will be the norm in just a few years."
A study last year for the 7x24 Exchange by Roger Schmidt of IBM and Suhas Patankar of Innovative Research projected that equipment heat loads will continue to rise through 2005, leveling off at server power densities of up to 1,200 to 1,500 watts per square foot.
"Over time, I think they're right on (target) with that," said Baer. "These trends aren't slowing down."
APC, Liebert and other manufacturers are focusing on equipment that allows data center operators to maintain "zones" of higher and lower demand, to provide more efficient localized cooling.
"In the future, you're going to see specific products designed for hot spots," said Baer. "We're targeting our products to be modular, and allow for incremental growth."
Down the line, air conditioning alone won't be enough, according to Baer.
"You really need to look at other solutions besides air cooling," he said.
Many data centers are engineered to keep water and other liquids away from servers and other electronics that could be damaged by wetness. But Evans says that may change as hot spots get hotter.
"There has not been a single data center we've seen that doesn't have some type of liquid in there somewhere," he said. "With proper precautions, many people don't see water as a problem in the data center."