Liquid cooling of servers as an upward trend in equipment for data centers

The exhibition SC (Supercomputing Conference) is dedicated to high technology. More specifically, supercomputers and related technologies are demonstrated at this exhibition. Every year, more and more liquid-cooled systems are being shown at this exhibition, plus the number of companies that demonstrate these technologies is increasing. Only a couple of dozen ago liquid cooling for servers was shown only by such well-known technology companies as Cray-2 and IBM. And that, for the most part, as a concept.

Now the number of manufacturers has grown, and the variety of technologies is impressive: the new SC showed both full-contact systems and full immersion systems. In general, the statement that fluid systems in some cases are much more efficient than air cooling is beyond doubt. But before the operation of fluid systems was problematic. Now there are new practical solutions that do not cause any difficulties in the work and maintenance.

In addition, the use of liquid cooling systems helps save money. According to experts, the reduction in operating costs in the case of working with liquids instead of air is up to 40%.
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The effectiveness of these systems can be judged by the fact that the list of the most productive computers in the world Top 500 presents several systems that use liquid cooling. There is a similar rating, Green500, which shows the most productive systems using those or other "green" technologies. There are even more powerful computers with liquid cooling systems, some of them are in the top-10.

The advantage of liquid cooling is the possibility of more dense placement of equipment. Heat is removed more efficiently than in the case of air systems, so the distance between the equipment can be much smaller than usual. Some server elements can work in a more active mode than usual, because, again, heat is removed quickly and without problems. And still - less noise than in the case of work with systems where there is active cooling with fans. Therefore, it is possible to avoid the “more servers - more noise” dependency. Liquid cooling systems also generate sound, but not as strong as their air "relatives".

There are many advantages here, but for the most part, everything is known about them. Let's better see which companies presented new technologies at the exhibition.

Aquila demonstrated the previously announced water-cooled Aquarius server system. This system is designed for placement in racks manufactured according to the Open Compute Project (OCP) standard. Clustered Systems became the partner of this company, which offered its own technology of cooled plates.

Asetek specialists showed their own version of direct contact liquid cooling systems. It uses warm, not cold, water. The project has quite a few partners. Among others, Cray, Fujitsu, Format, Penguin, HPE, NVIDIA and Intel can be called. The company's solution is already in use - for example, the QPACE3 machine (developed by specialists from the University of Regensburg), which is in 5th place in the Green 500 supercomputer rating, works just with a liquid cooling system.

The vendor CoolIT Systems has demonstrated some more direct contact system solutions. They work with Hewlett Packard Enterprise Apollo 2000 System, Dell PowerEdge C6320, NEC Blue Marlin, and Lenovo NeXtScale. This company also showed a micro-data center of its own design.

Ebullient showed a two-phase cooling system for servers inside data centers. It uses low pressure coolant. The coolant is pumped into sealed modules installed on the processors in the servers. The fluid receives heat from the processors and leads it through the hoses to the central unit for cooling. Such a system can work with almost any server.

Another universal system - CarnotJet System from Green Revolution Cooling . It, like the previous version, is compatible with almost all rack servers of any manufacturer. Such systems can be installed in specialized racks that are filled with special mineral oil.

LiquidCool Solutions (it was once already written about at Habré) presented updated solutions for complete immersion of electronics in a dielectric liquid. The company has developed this liquid independently. In addition, the manufacturer showed two new servers based on the Clamshell platform. The first server is the Submerged Cloud Server (4U server with 2U height for cloud platforms) and the Submerged GPU Server (2U with a 2U server GPU. The latest model can be equipped with four GPU cards or four Xeon Phi accelerators.


HPE Apollo

LiquidMips specialists showed the original version of the server cooling system with a single processor chip with immersion in the 3M Fluorinert refrigerant. Unfortunately, this is only a concept that has not yet been implemented in practice.

Not without Chinese manufacturers. Thus, the company Inspur Systems Inc. , a subsidiary of the Inspur Group, showed its liquid cooling systems with two types of solutions. One solution is to cool the chips by direct contact with the liquid. The Chinese argue that their system can significantly increase productivity and at the same time reduce operating costs.

Allied Control spoke about its achievement - jointly with other companies creating a 40 MW data center using a submersible cooling system. As a result, it was possible to achieve the installation of equipment with a density of 252 kW per rack. The system uses a 3M Novec dielectric fluid.

A well-known vendor from China, Huawei showed a new HPC FusionServer X6000 server with liquid cooling. It uses a branch from the processor using microchannels. Coolant flows through memory modules. The inlet fluid temperature is offered at around 50 degrees Celsius, which reduces the total cost and at the same time ensures high energy efficiency.

Fujitsu showed a new type of data center with "cloud" servers, storage and other elements. The data center uses a combined system of submersible liquid cooling, which is usually used for supercomputers. But Fujitsu applied the know-how and achieved the possibility of using such a system for standard servers.

Is it possible to use liquid cooling for servers already running?

Not usually. The use of LCD is usually set for new systems. Of course, if you wish, everything is possible, but in general, the data center will take a lot of time and effort to install liquid cooling systems for the already installed and working equipment. Probably, there are some systems of this type, but they are not very well known.

And you still have to modify the servers - in most cases you will need to remove the coolers, installing new cooling elements. We'll have to retool and racks. In most cases, this kind of modification will require not only a lot of time, but also a significant investment.

Whatever it was, and the market for liquid cooling systems is gradually growing. Analysts believe that in 2020 the market volume will be about $ 960 million. The exhibition SC is, one can say, a window into the future, which shows us how the market for cooling systems will change in the near future. LCD can be indispensable for high-loaded equipment, which is used in areas such as the development of AI, Big Data, etc.

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