What are data center infra protection systems?

Data canter infrastructure has to be protected from different threats which may result in disaster and loss of equipment and data stored in them. What are different threats to a data center infrastructure? They are from fire, water leakage in building and off course from rodents who can enter from any passages in building and cut your data cables bringing the services down. And then the worst thing is that tracing the location of cable which is cut and fixing it may be very difficult specially for cables passing under the floors through some duct.

Lest us see what are the systems available to safeguard our data centers from these hazards.

• GBFSS i.e. Gas Based Fire Suppression System
• VESDA i.e. Very Early Smoke Detection Apparatus
• WLDS i.e. Water Leakage Detection System
• RRS i.e. Rodent Repellent System

Let us see in detail, what they do inside the data center to protect the infrastructure.

GBFSS

Gas based fire suppression systems are sometimes also referred to as "clean agent". We have different types of fire suppression system for different types of fire e.g. electrical fire, combustible liquid fire and other combustible solid materials. Based on different types we have powder based, CO2 based and liquid based fire extinguishing methods. All these methods leaves some or the other residue which makes them unusable for data center IT equipment. Our requirement is to have a fire suppression system that doesn't leave its own residue after the fire is extinguished. For such requirements we use FM 200 [Heptafluoropropane] or NOVEC 1230 [CF₃CF₂C(=O)CF(CF₃)₂] fire suppression system which are released in high pressure inside data center on detection of smoke, and flooded inside data center to extinguish the fire. Multiple cylinders are used in bank whose output is connected together to a high pressure pipe that ends in the data center area. 

These pipes are terminated in multiple nozzles below raised floor, between raised floor & false ceiling and above false ceiling. Number of cylinders depend on the size of data center hall. Number of nozzles are spread across data center infrastructure via connected high pressure pipes to cover entire data center hall volume. The outlet of cylinders are controlled by solenoid valve. The solenoid valve is controlled by a control panel which sense smoke via connected smoke detectors deployed in data center room. These smoke detectors are again deployed inside entire area of data center. One set is below raised floor, other set below false ceiling and last above false ceiling. 

These smoke detectors in different regions are marked as different zones and the controller is normally programmed to activate the cylinder's solenoid valve once smoke is detected in at least two zones. This avoids any false signal from smoke detector and unnecessary release of gas as refilling of cylinders will involve lots of cost. This even require taking out cylinder from bank and refill at company outlet. Normally the solenoids are activated after few seconds of smoke detection, generally its 30 seconds programmed in controller. The controller is connected to a hooter as well which is activated the moment smoke is detected in two zones as programmed. This sends audio signal as well to the data center operators who are managing it. 

VESDA

As the name suggest its an apparatus which detects the smoke inside a room very quickly by sucking in sample of air inside the data center and detecting carbon particles in it. It is also known as "Aspirating Smoke Detection" as it sucks air in, for sampling of carbon particles in it. A network of pipe assembly is deployed inside the room where smoke has to be detected. These pipes have multiple air suction nozzles connected at different location. The network of these pipes finally terminates at VESDA equipment. VESDA has a small suction pump inside which pulls air from this pipe which intern collects air samples from different nozzles as shown here. This air sample is passed over a sensor inside VESDA where any traces of smoke are detected and air is thrown out from outlet hole.

This circulation keep going on, and if any traces of smoke is detected at the sensor, a hooter is triggered alarming support staff to take further action. This is much faster to detect smoke as it is doesn't wait for smoke to raise to ceiling level so that smoke detectors will detect and raise alarm or trigger gas release. It is actively pulling in the air sample and detecting smoke traces into it.

WLDS

Next threat to data center infrastructure is from any type of water leakage inside the room due to any pipe line passing near by the walls of room or any kind of seepage from any source. To detect water leakage WLDS is deployed whose sensors are spread across whole floor area below raised floor. The sensors are nothing but two naked metal wires running close to each other separated by an insulating material that keeps them apart during normal operation. The moment any water droplets are observed on this sensor, the connectivity between these two wires are established and is detected as water leakage in that area and raises a hooter.

Now the floor area may be very big and whole floor is covered with raised floor tiles (for more detail on data center infrastructure click here) and since the WLDS sensors are spread across whole floor, we should be able to know where water leakage is detected rather than searching on whole floor. For this the whole floor is divided in different zones like "Zone-1", "Zone-2" etc and the drawing of these defined zone is displayed at some place which is easily visible to data center maintenance staff. The WLDS has different connectors to connect sensors and those are also labelled as "Zone-1", "Zone-2" etc. So, the sensor wire from Zone-1 is connected to Zone-1 connector of WLDS and so on. When an alarm is triggered due to water leakage in any zone, the zone name is displayed at the LCD screen or indicated by light indicators on WLDS panel. This helps operators to view the drawing of room and reach the correct place of leakage based on zone number displayed at WLDS and take corrective action.

RRS

The next and the biggest threat to data center is from rodents which are very difficult to keep away. There are hundreds and thousands of network cable (Cat6 and Fiber) running inside the data center from one rack to other and from one device to other. Some cables also passes above false ceiling and some from below raised floor. If any one wire is cut, it is very difficult to identify that wire from bundle of wires running together. And rodents can enter from any small whole in building walls which are required to allow power cables and network cables to come inside data center building.

So, to keep the rodents away from data center area, rodent repellent system (RRS) is used. This generate high frequency audio signal more than 20Khz, somewhere around 25KHz to 55KHz which is beyond human audible range, but rodents can here it. And this high frequency irritates them and hence keep them away from data center infra. To produce such high frequency sound they do not use normal speakers as they cannot reproduce these frequencies rather a special piezoelectric transducer is used. 

Now again there is a chance that if we keep generating a fixed high frequency sound for longer time, rodents may get use to it and may not stay away or may be next generation of those rodents will be habitual to such sound and that is dangerous. To avoid this we use RRS which generate variable high frequency sound, means the sound frequency keep changing from say 25KHz to 55KHz. Hence there is no chance that rodents can be habituated to one particular high frequency.

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