Soaking the server in water turns out to be for... | Digital Literacy

Audit expert: Zheng Yuanpan

Professor of Zhengzhou University of Light Industry

In the Internet era, servers are essential core equipment for almost all data business companies. For several giants that have created the entire Internet world, servers are the arteries of their companies. What exactly does such an important facility do, and how do the big companies properly place it?

Cabinet Server

Source: Wikipedia

What is a server

Server , as the name implies, is a machine that provides services. Depending on the type of service, servers are divided into file servers, database servers, application servers, and WEB servers. Although there are many types, its main function is very simple, that is, to store, transmit, and process various data . We can happily watch videos, read news, shop, chat, and play games on various websites and apps, and the support of servers is indispensable. The server is essentially a high-performance computer, which is not much different in structure from the computers we use in daily life. It also has hardware such as CPU, hard disk, and memory stick. It’s just that it is generally not equipped with external devices such as monitors, keyboards, and mice. When maintenance or specific operations are required, they can be connected.

Server room source｜Sohu

Since servers are responsible for processing and saving the data generated by various activities we conduct on the Internet, servers, especially those from large manufacturers, have higher requirements for hardware performance, stability, and reliability. Taking the CPU, the core component of the host, as an example, the top CPU currently adapted for personal computers, the Core-13900K, and the server-specific CPU, the Xeon-8360H, the Xeon has a slightly lower single-core frequency, but other parameters are much higher than the 13900K, and the data centers of large manufacturers usually require hundreds of thousands of servers to run at the same time. Although personal computers and servers are both computers, the two are not at the same level in terms of computing power. The number of operations that need to be performed per second by large server clusters may reach trillions per second, while ordinary personal computers only perform about tens of billions of calculations per second.

Parameter comparison between PC CPU and server CPU

Source: Bilibili@Talking about three circles

When servers perform such a huge amount of calculations, they not only consume a huge amount of electricity, but also generate a lot of waste heat . If the heat is not dissipated in time, the temperature of some core components such as the CPU will rise rapidly. Once the temperature reaches above 85 degrees, it is very likely to cause equipment failure, and then cause the server to crash, which is what we often call "server explosion". Server crashes may require downtime for maintenance at the least, or data may be destroyed or even lost at the worst. This is undoubtedly fatal to Internet giants where data is the heart, so creating a safe and good working environment for the server is undoubtedly a top priority.

Why put the server in water?

In order to maintain the normal operation of the server, solving the heat dissipation problem is of utmost importance. The traditional heat dissipation method is mainly through air conditioning refrigeration and heat dissipation . Some top-level air-cooling equipment has a high heat dissipation efficiency, but it also consumes a lot of electricity to maintain the operation of the air conditioner. In 2020, the electricity consumed by China's data centers was about 204.5 million kWh, accounting for 2.7% of the total social electricity consumption. The huge power consumption will undoubtedly increase the operation and maintenance costs of the server and will also increase more carbon emissions. In order to reduce costs and maintain the environment, many Internet giants have begun to consider using more efficient, energy-saving and clean heat dissipation methods.

In recent years, major data centers have gradually replaced traditional air cooling with liquid cooling . Among the liquid cooling solutions, the more efficient ones are cold plate type and immersion type. The cold plate type is to install a heat-conducting cold plate under the CPU, and use low-temperature liquid to flow through the cold plate to remove heat. The immersion type is to place the server in liquid and directly remove heat through the liquid.

Liquid cooling is not only more efficient than air cooling (water has a heat dissipation efficiency 1,000 to 3,000 times that of air), but it also almost completely avoids the vibration caused by air cooling during operation, effectively reducing the failure rate of equipment. Some Internet industry giants, such as Microsoft and Alibaba, have also come up with ways to use natural water to dissipate heat for servers.

Alibaba has placed its servers on the shore of Qiandao Lake in Hangzhou. The water temperature in the deep layer of Qiandao Lake is maintained at around 17 degrees Celsius all year round. Alibaba has installed a special water purification device at the bottom of Qiandao Lake to purify the impurities in the water and directly transport it to the server room for cooling. The cooled water will be discharged to the Central Axis Creek of Qingxi New City, flowing over a distance of 2.5 kilometers and flowing back into Qiandao Lake after natural cooling.

The entire cycle achieves zero pollution and saves more than 80% of cooling energy consumption, making the PUE (Power Usage Effectiveness, also known as power usage efficiency, PUE = total data center equipment energy consumption/IT equipment energy consumption, the benchmark is 2, the closer to 1 the more efficient) of Alibaba Qiandao Lake Data Center an average of about 1.3, saving Alibaba nearly 10 million kWh of electricity consumption each year.

Alibaba Qiandao Lake Data Center

Source｜See watermark

Microsoft's approach is more direct. In 2018, after Microsoft put a solid shell on 864 servers, it threw them directly into the cold seabed of Scotland at a depth of about 36 meters, using the low temperature of the seabed to dissipate heat. In addition, the convection intensity of the ocean is higher than that of lakes and other waters, and the heat dissipation efficiency will be higher. In 2020, Microsoft recycled these servers, and found that the failure rate of servers placed underwater was only one-eighth of the failure rate of servers on land.

In addition to heat dissipation, Microsoft also considered other factors. For example, about one-third of the world's population lives by the sea. The economies of cities located by the sea are relatively developed, and placing servers by the sea is more conducive to serving these people. At the same time, the Onyx Islands in this sea area have tidal power stations that can provide sufficient energy for the servers.

Microsoft's servers under the sea in Scotland

Source｜pic4.zhimg.com In addition to water, it can also be placed in the mountains

There are many advantages to placing servers in water, but it also seems a bit troublesome when maintenance is needed, and many factors need to be considered, such as the server's waterproofness, corrosion resistance, and biological erosion resistance. Therefore, some manufacturers, such as Tencent and Huawei, choose to place their servers in caves.

Guizhou Gui'an is a summer resort in my country and is also the location of Tencent Qixing Data Center and Huawei Qixing Lake Data Center. Gui'an was chosen as the data center because it has many advantages.

Climate: The temperature is relatively low, with the annual average temperature being only 15 to 16 degrees Celsius. Even the highest temperature in summer does not exceed 25 degrees Celsius, and the temperature difference between day and night is small.

Geographical environment: Gui'an has an open area, high vegetation coverage (80%), stable geological structure, and is not prone to natural disasters such as earthquakes.

In terms of energy supply: the average electricity price in Gui'an New District is only 0.35 yuan/kWh, which is more than half lower than the national average price of 0.77 yuan/kWh, which is very cheap.

The above advantages make Gui'an particularly suitable for hosting servers.

Tencent has dug six tunnels, five horizontal and one vertical, in the Qifengpo Mountain in Gui'an. The five horizontal tunnels are all oriented north-south, with a tunnel area of ​​about 40,000 square meters and about 300,000 servers placed inside. The five horizontal tunnels are numbered B1, B2, B3, B4, and B5, of which B1 is the power tunnel, and B2 to B5 are IT equipment tunnels. Two shafts are also set above each tunnel for ventilation. When working, the outside wind flows directly from the power tunnel, is filtered and further cooled after passing through the refrigeration module installed therein, and then enters the IT equipment tunnel to exchange with the hot return air generated by the IT equipment during operation, and then is discharged from the shaft. This not only makes full use of the external cold source, but also avoids the potential impact of direct use of external air on the equipment.

After testing by the Ministry of Industry and Information Technology, the PUE limit of the Qixing Data Center can reach 1.1; the average PUE of other domestic data centers is 1.73, with significant energy-saving effects.

Tencent Seven Star Data Center

Source | Baidu

In the future, human society's demand for computing power will only increase, and issues such as data center site selection, operation and maintenance energy, and carbon emissions will become increasingly prominent. Seeking appropriate solutions to promote the development of the data center industry in a greener and more efficient way will definitely become an important trend in the future information industry.