A surprise report of 'It rained' in Facebook's data center, what is the reason?

Companies that are deploying Internet services globally, such as Google · Twitter · Facebook, have constructed and operate a data center that installs and operates mainframes and servers. An unbelievable episode that "clouds have formed and it rained" in the Facebook data center just completed is being introduced with reasons in the blog media · Medium .

It Was Raining in the Data Center - Member Feature Stories - Medium
https://medium.com/s/story/it-was-raining-in-the-data-center-9e1525c37cc3

In April 2011, Facebook's first data center was built in the Princeville , Oregon, USA. It is approximately 13,700 square meters in size, it offers energy-saving functions to recycle the heat of large-scale cooling system and server · State-of-the-art equipment such as a new uninterruptible power supply (UPS) capable of reducing power consumption by 12% It was equipped. The number of users of Facebook at the time exceeded 300 million people and was constructed to shift from leasing the data center of another company in consideration of the increase of subscribers and further expansion of services.

by Intel Free Press

A few months after completing the data center of the Plainville building, a phone called Jay! Parque, who was Vice President of infrastructure engineering at Facebook, got a cloud at Jay! Data Center! It was. When Mr. Parek asked "Outdoor story?" Voice in a panic with "That's not it! Clouds are in the data center!" The content of the phone was a surprise report saying "It was raining in the data center and it rained".

The data center houses large-scale servers and networked computing equipment, and we are always doing calculations necessary to support cloud computing. The data center uses more than 100 times the electric power of a normal office building, and a considerable amount of heat is generated from the server.

by Lance Albertson

In the data center constructed in the prime building, a cooling system using external heat and vaporization heat of water was introduced. This system has a structure in which two rows of "passage through which cold air flows" and "passage through which hot air flows" are alternately arranged. The former is a place where a server is placed or where people come and go, the latter flows because the exhaust of the fan flows It was a place of. The following image is a passage to take in outside air and let it flow to the cooling system.

by Lance Albertson

However, due to the operation control error of the cooling system, exhaustion of high temperature / low humidity came to flow into the cooling system was all cause.

In general, the higher the temperature of air, the larger the amount of water vapor that can be contained in the same volume " saturated water vapor amount " will increase. In this case, first of all, the computer that calculated the relative humidity judged that the computer which calculated the relative humidity "can contain water vapor" by the high temperature low humidity air flowed into the evaporation type cooling system, As a result of spraying and humidifying, the amount of moisture in the air sharply increased compared to the amount that should be originally.

by Robert Scoble

Then, air that exceeds 95% relative humidity will flow into the passage through which cold air flows at about 26 degrees or more. As a result of the rapid cooling of the air which normally contains an unavoidable amount of water vapor, the water vapor is condensed and clouds are generated. That's exactly "cloud (cloud) has been created on the cloud computer".

Luckily the server itself seems to have not been seriously damaged, but as a result of the investigation, it turned out that some power supply equipment failed because water accumulated on the concrete floor. It did not really rain heavy rainfall from the cloud, but it was the result of condensation of water vapor on the concrete floor.

From this reflection on Facebook, Facebook revised all the guidelines to ensure thorough humidity management in the data center. However, as it is a cooling system that uses outside air, it is necessary to manage humidity in accordance with the weather forecasting system, and it was difficult to completely control the humidity. For that reason, it seems that we finally implemented a rubber seal around the power supply and the server. Mr. Parik talks with jokes "I put on a rubber raincoat on the power supply".

In addition, Facebook judged that "it is better to cool down the server with cooler climate and hydropower generation", and in 2016, huge data near the Arctic Circle in northern Sweden We have established a center.

Zuckerburg CEO publishes ecologically clean huge server facility at the highest level supporting Facebook - GIGAZINE