Earthquake-resistant server cabinets: what's special about them?
Earthquake-resistant server cabinets are usually used in areas with high seismic activity, where earthquakes can damage equipment or cause critical system failures. They are vibration-resistant structures capable of withstanding strong shocks and sudden changes in load, which can save the operation of servers and related systems in a critical situation.
The main danger to the data center in an earthquake:
Only part of the risk associated with earthquakes is that IT equipment may fail. A more serious risk is how this will affect data center customers and running applications. Basically, data centers provide computing power, which is easy to increase simply by buying equipment, but ensuring uninterrupted operation requires more complex infrastructure planning. The loss of 5% of equipment due to an earthquake may even be unnoticeable to customers if their data is replicated elsewhere and a fault-tolerant configuration is configured. But downtime has the greatest impact on customers, especially if the client's business is running continuously.
NEBS Seismic Zone 4 and GR-63-CORE standards
The Network Equipment System Standard (NEBS) defines how manufacturers' products withstand extreme conditions. It was created for the Central Office of the Bell regional operator company in the 1970s.
Earthquakes are divided into low- and high-risk zones, measured in "ground acceleration". The higher the zone, the higher the threat of potential damage to property. If the data center is located in a high-risk area, not only the racks must comply with the NEBS standard, but also the infrastructure must meet the specified criteria.
Telcordia NEBS Requirements: Physical Protection describes in detail the measures to comply with the standard. Server racks in this case are only a small part of the criteria required to comply with the NEBS standard. Here are some examples of what companies should pay attention to:
- Fire safety
- Temperature and humidity
- Protection against shock, vibration and earthquakes
- The content of harmful substances in the air
- Noise level produced by the equipment
- Floor load generated by equipment
GR-63-CORE is a standard developed by the American Institute of Communications (ATIS) to assess the stability of electronic systems and equipment to the effects of seismic loads. It is used to assess the stability of telecommunications infrastructure in areas with high seismic activity. The standard takes into account the impact of horizontal and vertical components of seismic loads on equipment.
What problems arise in the server cabinet during an earthquake
Various types of deformations occur in the elements of the server cabinet, including bends, twisting, stretching and compression. At the same time, both distributed and concentrated loads act on the farms, which can lead to damage to structural parts and even the collapse of the cabinet.
The load vectors during an earthquake can also be different and depend on the ratio of the mass distribution inside the cabinet, overall dimensions and height of its location. Usually the load vectors are directed horizontally and vertically, but they can also be in other directions.
What is the structural difference between a conventional server cabinet and a seismic-resistant one
To achieve seismic stability of server cabinets, it is sufficient that the cabinet does not deform during the loads being tested. There are also more expensive methods like mounting on bearings, but this generally applies to the design of data center floors, and this is the topic of another article. To increase the rigidity of the server cabinet , the following methods are usually used:
- Increased structural rigidity due to thicker walls and frame.
- The use of reinforced fastening systems - such systems guarantee reliable fixation of the cabinet to the floor and walls of the data center.
- Optimization of load distribution inside the cabinet - this can be achieved by installing special diagonal stiffeners to reduce dynamic loads.
- The distribution of equipment inside the cabinet in such a way that the center of gravity is closest to the bottom of the case, which ensures a more stable position of the cabinet in case of earthquakes. As a rule, UPS and battery compartments are installed at the bottom, then storage, servers above and switches and patch panels at the very top.
- Earthquake-resistant server cabinets are delivered assembled, as they usually have a welded frame.
How earthquake-resistant cabinets are tested
During the tests, the cabinet is loaded to its maximum capacity and installed on a vibrating table that simulates an earthquake, creating shaking in three directions (one direction at a time) with different intensity levels equivalent to an earthquake in a specific seismic zone.