Immersing servers in liquid can be a good thing

If you’ve ever accidentally spilled tea on your laptop, you understand why liquids seem like one of the things you want to keep out of data centres, not in them. But one firm says surrounding server components with water and liquid coolant is an ideal way to save energy and money.

The UK-based Iceotope launched its new liquid-cooled server technology today at the Supercomputing 2009 conference in Portland, Oregon.

“We have spent 18 months developing this technology in stealth mode, with input from a number of interested customers,” said Dan Chester, CEO of Iceotope. “We believe that we will see a huge growth in the use of liquid-cooled servers as people see the ease with which these systems can be deployed.”

Iceotope claims its system is the first to use modular “liquid immersion” of server components and can reduce data centre cooling costs by 93 per cent. That’s no small feat when you consider a data centre with around 1,000 servers can spend more than $260,000 a year on air cooling systems.

With Iceotope’s technology, that cost could go down to about $17,500 a year, the company claims.

The modular liquid immersion system also lets data centre operators pack servers more tightly without having to worry about cooling efficiency, reducing the space needed by as much as 84 per cent, according to Iceotope.

Iceotope’s “end-to-end liquid” approach entirely eliminates air in the heat transfer path between server components and the air outside the data centre and replaces it with a series of liquids, including water.

Because it can hold far more heat by volume than air, water is already used for heat transport in many data centre facilities, although usually outside of the main server room. As demand for data centre services and power have grown, various attempts have been made to bring water closer to the servers, including “in-rack” water cooling that chills the air near servers and “component-level” cooling that brings water to the processor via locally-connected “water blocks.”

Iceotope’s technology takes liquid — in the form of an inert synthetic coolant, rather than water — directly down to the component level. The entire contents of each server are immersed in a “bath” of coolant within a sealed compartment, creating a cooling module. These cooling modules fit into a chassis, several of which can be mounted in an industry-standard 19-inch data centre rack. The chassis provides each module with electrical power and a connection to a local water circuit that pumps water through channels in the connected modules to remove heat from the closely-coupled (but sealed) motherboard compartment.

The chassis has a further water-to-water heat exchanger that transfers heat to a building-level water circuit, which could be pre-existing or newly installed. The improved thermal efficiency of the earlier stages, due to the replacement of air with liquids, means that this water can be provided at higher temperatures (requiring little or no chilling) and/or in lower volumes than the air in an equivalent air-cooled system.

“It is increasingly clear that as demand for high-efficiency/high-density data centres increases, a substitute for air cooling is required,” said Liam Newcombe, director of research & policy at Romonet Limited, an IT energy efficiency firm. “Water is much more efficient in terms of its thermal transfer properties; the main question is how best to couple the water to the servers. Of the different approaches that we have seen, the Iceotope direct liquid immersion seems to have clear benefits in terms of thermal performance and operational management.”