Microsoft using two-phase immersion cooling

The tech giant is employing two-stage immersion cooling at its Quincy, WA data centre.

Microsoft has moved beyond liquid cooling in one of its data centres, using two-phase immersion cooling to maintain temperature on active production servers.

Husam Alissa, principal hardware engineer for Microsoft, said, “We are the first cloud provider that is running two-phase immersion cooling in a production environment.”

The two-phase immersion system involves submerging the servers in a bath of non-conductive fluid, which has a low boil point at 122 degrees Fahrenheit (90 degrees lower than water). The continuous boil takes heat away from servers, allowing them to operate at full capacity without danger of overheating.

The boil also creates steam, which is funneled into a cooling condenser and then ‘rained’ down on the servers – creating an efficient, closed-loop cooling system.

Liquid Cooling vs. Immersion

Liquid cooling – using liquid to cool air inside the data centre – has been in use by cloud providers in one form or another for years. As demand for data services rises, manufacturers have responded by creating hardware that can process at higher volume and faster rates. But in doing so, they generate increased amounts of heat, making it difficult to efficiently cool a complete data centre with millions of processes running concurrently.

Single-phase liquid cooling generally involves moving cold water through pipes or across cold metal plates in raised flooring, lowered ceilings, or in server racks themselves to maintain acceptable air temperatures. In fact, in 2018 a consortium of leading cloud providers including Baidu, Microsoft, Google and Facebook began working together on an open specification for liquid-cooled server racks.

Immersion cooling, instead, involves submerging hardware into a fluid bath – not water, but a non-conductive, insulating, dielectric fluid; directly lowering the temperature of equipment without interfering with processing.

Tested by Bitcoin

Immersion cooling technology was pioneered by cryptocurrency miners looking to improve the operations and efficiency of large-scale crypto-mining farms. In fact, a scientific paper published back in 2014 reviewed the pros and cons of immersion cooling at that time, and the implications for high performance computing (HPC).

Benefits of Two-Phase Immersion Cooling

A working two-phase immersion cooling system for the data centre may offer significant benefits, including:

Sustainability.

Immersion cooling uses less water and is more efficient in energy usage than traditional cooling systems, helping data centres reduce their impact on the environment. Moreover, because immersion cooling allows equipment to operate at capacity without danger of failure due to overheating, data centres can maximize processing on the equipment they have, rather than expanding their footprint to make up for underutilization.

Performance.

One of the key takeaways from Project Natick, which involved submerging Microsoft servers into the Scottish sea, was that underwater servers had 1/8 the failure rate of their sister servers on land. This was attributed to the lack of humidity and oxygen affecting the underwater servers: a benefit that Microsoft believes will translate to servers similarly protected in an immersion cooling system.

Edge Computing.

Two-phase immersion allows for more compact footprints than a traditional data centre. Equipment can be packed tightly together in a compressed space, reducing the need to build out a complete data centre facility. And if the closed-loop immersion system is successful, and requires less maintenance or frequent replenishment of fluid it can be placed anywhere – even underground. This opens up opportunities for edge computing, creating a flexible network of smaller, immersion-cooled data processing units that are physically closer to the point of need.

Husam Alissa notes that liquid cooling can impact the entire data centre ecosystem, including “higher density racks that could lead to a smaller data center footprint and lower their center energy consumption from a mechanical cooling perspective.” Additionally, he notes, servers could end up with a more compact design as well, as internal fans for cooling servers could be removed in these systems.