Water-cooled server racks remain a rare thing in data centres. But IBM's move last week to offer an add-on water-cooling unit for its Intel-based xSeries servers and other systems should increase the technology's visibility as a potential solution to heat problems.

The cooling project is dubbed "Cool Blue," and the first related product is the IBM eServer Rear Door Heat eXchanger. This is a door that can be retrofitted on the company's standard 42U enterprise rack (1U is 1.75 inches) that houses its xSeries Intel-based processor line.

The chilled water supply that flows through eXchanger comes from a data centre's existing air-conditioning systems. IBM claims that it will remove up to 50,000 BTUs, reduce server heat emissions by up to 55 per cent and lower energy costs by 15 per cent.

The water-cooled system is intended to address the problem of hot spots in a data center, said Tim Dougherty, director of IBM's e-Server blade centre.

IBM believes the technology will be of interest to data centre managers who have controlled heat through server configurations and improved airflows but still have areas in their data centres with high temperatures. "What this will do will effectively alleviate those hot spots," said Dougherty. The technology will likely be of most interest to data centre customers who can't easily expand floor space, he said.

Water cooling already is on the minds of some users. For instance, the topic was briefly discussed last week at a meeting of the Central Indiana chapter of AFCOM, an association for data centre managers. "Nobody was buzzing with enthusiasm," said Jamie Man, who heads the chapter.

Man isn't dismissing water cooling, though. "The way technology is moving to blade servers, I can see a benefit to it, but it will be somewhat down the road," said Man, an architecture and operations infrastructure manager at ArvinMeritor.

Shifting back
IBM long used water cooling in its mainframes but gave up on the technology as it shifted to smaller and less-expensive versions of those systems a decade ago. Now, the increasing density of blade servers is giving water cooling new life.

IBM's eServer Rear Door Heat eXchanger, code-named Cool Blue, is designed to handle the heat produced by large racks of blades and other high-density systems. It can be retrofitted on the company's standard 42U enterprise rack, which houses xSeries servers, and it's also available as part of IBM's Linux-based Cluster 1350 system. 1U is 1.75-in. high.

Heat eXchanger pricing starts at US$4,229, plus installation costs. The device uses chilled water from existing air-conditioning systems in data centres. IBM claims that the eXchanger will remove up to 50,000 BTUs, reduce server heat emissions by about half and lower energy costs by 15 per cent.

Kent Howell, manager of computer operations at Ameren's AmerenIP subsidiary said water cooling is a technology "that may clearly have a value in the future, as servers get smaller and hotter and there are more and more of them filling up data centres."

Water cooling isn't in the immediate future for Howell -- his data centre has excess air-handling capacity. But "a year from now, it may be a whole different story," he said.

Cool Blue "is something we would look at," said Jim Krause, CIO at Chicago Mercantile Exchange. "The blade-server issue that thing is addressing is obviously a concern."

Krause noted that most data centres weren't designed to handle the high levels of heat generated by racks of small servers (see story).

IBM's Heat eXchanger
Charles King, an analyst at Pund-IT Research, said that because of the heat generated by newer processors, many IT managers "are suddenly looking at power and heating and air-conditioning requirements that are going off the scale." IBM's offering could help users "buy some time" before they have to rebuild or retrofit their data centres, King added.

Vendors such as Knurr and APC already offer water-cooled units for servers. But Illuminata analyst Gordon Haff said IBM will bring credence to the technology because of its prior experience with mainframes.