It can get devilishly hot in some parts of a data centre. All those servers packed in like sardines with their processors humming away 24/7 can generate a lot of heat. Even with industrial-grade Computer Room Air Conditioner (CRAC) units, some data centres are plagued by hot spots the units just can’t cool.
IBM’s new Cool Blue component tackles those pesky hot spots. Designed to fit on the back of an IBM enterprise rack like a door, Cool Blue (or the IBM eServer Rear Door Heat exchanger, a duller if more accurate name) operates like an old-fashioned radiator, except that it circulates chilled water. Cool Blue doesn’t require any special plumbing beyond a hose to connect it to the existing chilled water supply pumping through the CRAC units.
“Cool Blue eliminates hot spots without having to redesign the data centre,” says Tim Dougherty, director of Blade Servers at IBM. “It’s totally optional, and it helps in the overall intelligent design by reusing existing resources where you can.” At a cost of about US$4200, Dougherty points out that Cool Blue can be a cost-effective alternative to adding extra CRAC units, which can cost tens of thousands of dollars — and may still not address hot spot problems resulting from constraints in the data centre’s design.
“The problem you run into at a lot of data centres is that the air that comes out of a rack of servers is hot, but there isn’t enough local capacity within a particular area to cool that air. Therefore, it gets hot and the air gets sucked back in, and then it’s hotter still, and so on,” says Gordon Haff, a senior analyst at Illuminata, a research consultancy based in Nashua, NH.
CRAC units cool the ambient air in an undifferentiated fashion, whereas Cool Blue runs chilled water to a specific area, eliminating up to 55 per cent of the heat before it enters the air cycle, according to Dougherty. By easing the burden on CRAC units, energy costs can be reduced by up to 15 per cent.
“You don’t necessarily want to put Cool Blue on every rack; the whole idea is to attack those hot spots,” he says. “We believe in the general environment of a data centre. Cool Blue could handle about 15 per cent of the cooling, so there would be savings in energy costs.”
Cool Blue is a response to a growing problem for many companies in recent years. The typical customers will be companies with data centres in urban areas like Toronto or New York, where real estate is expensive and expansion is difficult, or in older data centres that may not be state of the art, says Haff.
But these aren’t the only companies that may have cooling problems.
“Computing infrastructure tends to expand, because systems are being used for more and more. A company doesn’t need to be growing enormously for this, and even companies that are relatively stable tend to add computing infrastructure,” he says. “We can put more and more computing power into a smaller and smaller amount of space, and we’ve reached the point where the limiting factor now is dealing with heat and power.”
Haff points out that Cool Blue is a specific solution for hot spots, but is not the right product for expanding a data centre’s cooling capacity. “If you have high-enough capacity air conditioning, and you have your data centre arranged in an optimal way, you don’t necessarily need this. In an ideal environment, this does not allow you to increase the number of servers, as Cool Blue cools the outflow air only, not inflow.”
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