Tsubame-KFC: Japan Submersible Cooling Supercomputer

In Japan, sometimes they come up with and create very strange devices, however, here they usually create unique IT projects that quickly become famous. For example, Tsubame-KFC is a supercomputer that uses an immersion cooling system. About such a cooling system, where the working equipment is immersed in a coolant (as it is, mineral oil), they wrote more than once on Habré. But there are practically no posts about Tsubame-KFC. But this is a supercomputer that ranks first in the ranking of Green 500 supercomputers. The rating itself was created to evaluate the world's most energy-efficient supercomputers.

Of course, this rating is not as famous as the rating of "ordinary" supercomputers, but, nevertheless, it is worth paying attention to it. Interestingly, in this rating, the first 10 positions are now occupied by computer systems, including both conventional Intel processors and NVIDIA GPUs with coprocessors.



It is worth paying attention to the computer system mentioned above. The fact is that Tsubame-KFC (this system is installed at the Tokyo Institute of Technology) works with fairly high efficiency, 4.5 gigaflops / watt. This is currently the best indicator among all supercomputers. The second line in the ranking is occupied by the Wilkes system (works in Cambridge) with a margin of 25%. The efficiency of this supercomputer is 3.6 gigaflops per watt.

Tsubame is a supercomputer that is constantly evolving and being refined. So, the news about Tsubame still flashed on Habré, back in 2008. Since then, the system has been greatly improved. Here, not only system performance indicators have been improved, but also, to a large extent, energy efficiency indicators.

The Tsubame-KFC system (by the way, “Tsubame” in Japanese is a bird, and KFC stands for Kepler Fluid Cooled) uses two Intel Xeon E5 (Ivy Bridge) and two NVIDIA Kepler K20 GPUs in pairs. All this falls into a single cooling case created by Green Revolution Cooling. The cooling case itself is called CarnoJet.

To compare the energy efficiency of the Tsubame-KFC system, you can take the most powerful Tianhe-2 supercomputer at the moment from the corresponding rating. Tianhe-2 shows a result of 1.9 gigaflops per watt. The performance of this system is 33.86 petaflops (quadrillion operations per second). As for Tsubame-KFC, it has already been written above that its result is 4.5 gigaflops / watt.



By the way, at the SC13 conference on supercomputers (it was held on November 23, in Denver, Colorado, USA), immersion cooling was one of the most popular topics for discussion. This type of cooling, according to participants, is more efficient than air cooling systems. Of course, a completely different system is used here, where additional equipment and materials are required. However, the submersible computer cooling system is becoming more popular.

For example, in China, a large data center has recently been built (the owner company is not named), where a two-phase immersion cooling system is used. Such a system is usually applied to electrical equipment (transformers, inverters), as well as for cooling supercomputers (as mentioned above). Now, as we see, an immersion cooling system is also used for data centers, where money is saved on the installation and operation of conventional cooling systems. Among other things, the density of the equipment in this case is 10 times higher than in the case of air cooling.

The 500kW Chinese data center in question, as a result, fit in a regular container. It can be assumed that over time, the submersible cooling system will still take its rightful place within the data centers. Most likely, it will not supersede the air cooling system, but it will become quite popular in some regions (and with the growth of popularity, the price of individual components and the entire system as a whole will fall).

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