Liquid Cooling Can Prevent A Data Center Melt Down

There may be a liquid-cooled computer in your data-center's future.

The way things are going now, it won't be long before heat generated in the data center starts to become a larger and larger problem.

"Heat," an old friend used to say, when speaking of electronic equipment, "is the enemy." And that's true because electronic components are designed to operate inside a given temperature range, as are hard-disk drives. Get outside that temperature range, and things start to go haywire. Electronic components will begin to carry too much current, and may go into a condition called thermal overload. If that happens, you'll know it. With today's servers, you'll get an entry in the error log, and you'll get a server that starts operating more slowly than it should. When you check the server log, you can see what happened.

"If there is a heat problem, " says David Schaller, technical marketing program manager for Rittal Corp., Springfield, Ohio, "you'll know it because you start getting servers that have gone into thermal overload."

If, or when, that happens, you'll be forced to handle the problem somehow. The solutions range, Schaller says, from things as simple as moving equipment around, to redirecting the airflow under the raised floor, to installing liquid-cooling systems to get rid of those hot spots.Liquid cooling has been widely used with mainframe computers and supercomputers, but so far it hasn't made many inroads into the small-server market. That may change: processors are generating more and more heat, and disk drives are hotter as they spin faster and the air friction inside the head-disk assembly generates more heat. So it may be that there's a liquid-cooled computer in your data center's future.

If you Google "liquid cooling computer," you'll get almost 500,000 returns, most of which aren't suitable for your particular needs. For example, the Apple PowerMacG5 computer uses liquid cooling, the entry says. You can see what Apple says about its liquid cooling here. Other liquid cooling systems seem to be aimed at game players who are severely over clocking their systems.

But there are some server solutions available and in the works. Schaller touts two products from Rittal, and says he knows of other manufacturers who are working on liquid cooling systems, and he expects to see them in the market within about six months.

The basic principle in liquid cooling is to employ a liquid to remove heat, just as with a car radiator. Because of the greater density of the liquid than air, the liquid is much better at heat transfer than is air. Schaller says that water, in particular, can have as much as 1,000 times the heat transfer of air, given similar fluid flows and time.

Schaller's products include the Power Cooling System, which delivers liquid directly to a processor heat sink. This one requires piping inside a case or rack, of course, so the company is dicussing it with the large system OEMs, who, presumably, will offer a liquid cooling option on their energy-gulping servers.The other product is the Liquid Cooling Package (LCP). You hang the LCP on the side of a rack, or in some unused space inside a rack, and it works by using chilled water to cool air, which then blows horizontally in front of servers in the rack. The cool air gets drawn into the server cabinet, whether it's conventional or a case of blade servers, and drops the internal temperature of the box.

Liquid cooling may be coming of age, as processor complexity and speed, and disk rotational speed, continue to increase. You can spot the need if your servers start going into thermal overload. But thermal calculations are not easy (trust me on this one -- I found thermodynamics a nightmare many years ago). So the best thing to do would be to contact a manufacturer of a liquid cooling solution and get some expert evaluation in to the data center. If you need it, liquid cooling will take the heat off.

David Gabel has been testing and writing about computers for more than 25 years.