IBM researchers are counting on a 40 year-old technology to keep modern, state-of-the-art datacentres running cool and allow companies to squeeze more computing power from the electricity they consume.
These considerations are more important than ever. The power consumed by a rack of servers has risen from around 5kw of power per server rack five years ago to as much as 30kw today, thanks to the introduction of more powerful processors and denser blade servers. And the power-consumption levels will continue rising in the years ahead.
“People want more compute power and we can give it to them because we can package this into a smaller footprint, basically,” said Roger Schmidt, chief thermal architect and distinguished engineer at IBM’s server and workstation division.
The challenge that Schmidt and his colleagues face is how to dissipate the increasing levels of heat these systems generate. “We’re working on this all the way from the chip to the datacentre,” he said.
At the datacentre level, Schmidt sees an expanded role for water-cooling as a means to bring heat levels down.
Water-cooling, which uses small pipes filled with distilled or deionised water to dissipate heat, was first used by IBM to cool mainframe computers during the 1960s. The technology, which was used in more than 90 per cent of mainframes by the mid-1980s, was given a second lease on life in 2005, when IBM introduced its line of Cool Blue water-cooling products.
One such product is IBM’s $4,299 Rear Door Heat eXchanger, which attaches to the rear of a server rack. Four inches thick and weighing about 32kg (70 pounds) when filled with water, the Rear Door Heat eXchanger, can absorb more than half of the heat coming from a server rack, according to IBM.
IBM’s water-cooling systems, as well as competing products from companies like HP, offer several benefits for datacentres. Most importantly, water can absorb more heat than air, and the pumps required to circulate water in a cooling system consume less power than air-conditioning systems.
And IBM plans to expand its line of water-cooling products in the months ahead. “We’ve got other enhancements coming out shortly,” Schmidt said, declining to elaborate on specific details.
One potential enhancement is to extend water-cooling from the rear of the server rack to specific components, such as processors – as was done with some IBM mainframes. “Once you bring water to the rack, you've got a lot of options,” Schmidt said.
Convincing datacentre operators to pipe water through racks filled with expensive servers and invaluable data is not always easy. The easiest to convince are those IT managers with experience from the days when water-cooled mainframes were the backbone of large corporations, Schmidt said. But many remain nervous at the thought of water-filled pipes coursing through rooms filled with expensive servers and invaluable data – even though water is already a key component of all datacentres.
“Water cooling in datacentres is already there,” Schmidt said. “The chilled water that’s brought to the air conditioning units? That’s water and it’s in the pipes right above the server racks. We’re just plugging into that to apply that at the rack level.”