liquid cooled servers (Photo by Gene Twedt for Microsoft)

Microsoft cools data center servers in liquid-filled tanks

Microsoft is immersing hot server blades in liquid-filled cooling tanks in an effort to keep delivering more powerful data centers, even as advances in air-cooled computer chip technology have slowed.

The tanks at Microsoft’s Quincy, Wash., data centers are filled with a fluid made by 3M that has "dielectric properties," permitting the servers to run "overclocked" while venting heat through the fluid. As they cool, vapor rises from the fluid, hits a condenser and changes again to liquid, falling back into the tank. This creates a “closed loop cooling system,” Microsoft said in an innovation story.

“Air cooling is not enough,” said Christian Belady, distinguished engineer and vice president of Microsoft’s datacenter advanced development group in Redmond. Heat transfer in liquids, he explained, is significantly more efficient than air. “That’s what’s driving us to immersion cooling, where we can directly boil off the surfaces of the chip.”

Microsoft compared the use of these cooling tanks to its own undersea server cooling experiments with Project Natick. In those experiments, a submersible container filled with servers was set down on the cold sea-bottom floor.

"We brought the sea to the servers rather than put the datacenter under the sea," explained Husam Alissa, a principal hardware engineer on Microsoft's datacenter advanced development team, regarding the new, two-phase liquid immersion tanks. ”We are the first cloud provider that is running two-phase immersion cooling in a production environment,"  he added.

According to Microsoft, cryptocurrency mining farms pioneered liquid immersion cooling because it allows them to dramatically reduce overall power costs and dramatically increase the number of hashes calculated per second.

Practical applications

Microsoft is currently experimenting with using the cooling tanks to deal with bursty traffic, such as the traffic generated by Microsoft Teams meetings when people meet at the same time. The cooling solution is also seen as being useful to address high-performance Microsoft Azure artificial intelligence and machine learning workloads.

With the experiments, Microsoft is examining the notion that the cooling tanks will reduce failures. If so, it could make them suitable when deploying servers in "remote, hard-to-service locations." However, they may not be able outdo the failure reductions seen with Project Natick.

With that initiative, Microsoft pumped the undersea containers with nitrogen, which reduced corrosive effects.

"A key finding from Project Natick is that the servers on the seafloor experienced one-eighth the failure rate of replica servers in a land datacenter," Microsoft explained. "Preliminary analysis indicates that the lack of humidity and corrosive effects of oxygen were primarily responsible for the superior performance of the servers underwater."

This article was first posted to Redmondmag, a sibling site to GCN.

About the Author

Kurt Mackie is senior news producer for the 1105 Enterprise Computing Group.


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