Data centre density
9 March 2015 | 0
The issue of power and cooling is a significant one for those in the position of having to foot the bills for climbing density levels, according to Dushy Goonawardhane, business development manager for pre-fabricated data centres with Schneider Electric.
Kilowatts per rack
“Data centre density can be good or bad, depending on your perspective. It can be bad for people who built large data centres with a certain design in mind and now find that design no longer fits their purpose,” he said.
Most large data centres were built 10 or more years ago and according to Goonawardhane, were only designed to supply four or five kilowatts of power to each rack.
“At the time, rack density meant a power usage of one to two kilowatts per rack, and four or five kilowatts was the predicted use maybe for today, 10 years later. But then five years later, blade servers came into use, became mainstream and those power expectations started to look naïve,” he said.
“I remember around 2009 or 2010 having discussions about how rack densities were expected to climb to 60 kilowatts per rack. Data published by Cisco and some of the other vendors last year have shown that this hasn’t really happened, although we have done a few installations with very high density — one in China that went up to 50 kilowatts a rack, and one in Russia that went to 75 kilowatts. But those aren’t mainstream — they’re outliers,” he said.
So the message is that if you have not planned for your data centre design to evolve, you might be in trouble. But for those that did allow for change, then rising density isn’t necessarily an issue.
“For companies that went for modular development and which built out their data centres in smaller chunks in order to plan for future change then things haven’t been that bad,” said Goonawardhane. “They’ve been able to work with vendors who have introduced close coupled cooling equipment to capture heat at source on the thermal level and so on.”
So just what is driving the demand for higher density, and with it the problems associated with power and cooling? According to Davin Cody, sales specialist for HP’s enterprise group, the demand is coming not just from companies looking to achieve efficiencies but from those trying to keep up with growing demand for services.
“Density is driven by a demand for more services, more compute and more storage. It’s not density for its own sake — organisations are experiencing more demand and as a result have to provide more services and more virtual machines,” he said.