The challenges of data centre fire safety

The pivotal role of data centres and server rooms and their fundamental contribution to modern life is undeniable. And, with the amount of data stored doubling every 18 months, it is a rate that is only increasing with the ongoing development of AI. The oft-quoted figure of an estimated 90% of data being created in the last two years helps to put this in perspective. It is therefore relatively easy to appreciate just how devasting a data loss can be. The financial consequences for a business can be considerable, as can the potential reputational damage, with business closure in the event of a serious data loss being an all too regular occurrence. A basic consideration in maintaining the operation of a data centre is protection from fire, with a solid fire safety concept an essential component in any data centre’s business continuity strategy.

Business continuity is a fundamental tenet in the world of the data centre. With companies so reliant on their information systems to run their operations, any downtime can have significant and wide-ranging repercussions. A reliable infrastructure for data centre operations is therefore crucial, not only for the data centre itself but also for the customers that it serves. Integrity and functionality of the hosted computer environment are prime considerations in this process for a service in which such a high level of availability (business continuity) needs to be achieved. 

Single source option

The importance of business continuity is perhaps best illustrated by the requirement for a Tier 4 data centre to be fully fault tolerant and have an uptime of 99.995%. In terms of fire safety, this means that a detection, alarm and extinguishing system needs to be designed to keep the business functioning, even if a fire does occur. As such, early detection plays an integral part: the earlier a fire can be detected, the earlier the operators can be notified of the event and the earlier the required technical and organisational measures can be initiated.

Fundamental to this early response in the event of a fire is the interface between detection, alarming, control and extinguishing. Communication between the different elements is essential for the effectiveness of the complete system. This is a strong argument for adopting an integrated fire safety system from a single source.

Aspirating smoke detection

The heavy power loads that are a characteristic of data centres need to be considered in establishing an effective fire safety system. Such loads or a defective component in equipment can quickly lead to overheating or a short circuit. Electrical fires will often start slowly with a long period of overheating and smouldering before flames even occur. To detect overheating and avoid the onset of flames, very early smoke detection is required. If smoke is greatly diluted by high ventilation, aspirating smoke detection (ASD) will provide the earliest possible warning even when the smoke is undetectable by the human eye. Air samples are continuously taken at the danger spots, usually in the circular airflow as well as among the server racks, and carried to the sampling device. As soon as smoke particles are detected by the air sampler, a pre-alarm or an alarm is triggered, depending on the smoke concentration level. The response characteristic is determined according to the application. Sensitivity ranges from normal to high, allowing even a minimal smoke concentration to be identified unequivocally at an early stage. 

Aspirating systems can be up to a thousand times more sensitive than a standard point detection system. By combining this level of sensitivity with an environmental learning capability, it is possible for such a system to provide and maintain the optimum operating level and keep unwanted or 'false' alarms to an absolute minimum. Aspirating systems also usually have the capability to monitor their own integrity and, in the event of the system’s ability to detect smoke being compromised for any reason, an alert is raised. 

Shutting down equipment at the earliest indication of fire will stop even corrosive combustion gases from developing further. In a “gentle” shutdown, intelligent server management is activated to divert valuable data to neighbouring server racks. This can only be achieved by combining an appropriate software/hardware environment with the earliest possible fire detection. The final shutdown of power only takes place once the transfer of data is complete.

If such a “gentle” shutdown is considered too risky, an alternative method – aspirating smoke detection with verification by point-type detectors – may be used. In this system, the cooling system is shut down after pre-alarm while the point-type detectors verify the presence of combustion and trigger the extinguishing system.

ASD systems are available which operate through a dual wavelength technology to verify that particles aspirated in very low concentrations are actually smoke from a fire. Full integration of the device into the fire safety or management system ensures the safest operation possible because all the ASD warnings and possible maintenance messages are available at the management level to allow corrective measures to be taken. Recent developments have seen the introduction of newer generations of ASD technologies which mean that a single device can now cover an impressive area of up to 6,700 m2..  Even for Class A installations with the highest sensitivity requirements, up to 2,000 m2 of detection coverage is achievable with a single detector. This makes the technology ideally suited to applications typified by their large open areas, data centres being a prime example.

Preventing damage to HDDs

One of the fundamental considerations in designing an extinguishing system for a data centre application is to ensure that the chosen agent extinguishes the fire without harming sensitive electronic equipment. Water should therefore be avoided at all times. Furthermore, the agent must be environmentally friendly, safe for people working in the protected area, and cause no harm to the HDDs in operation.

Even though dry extinguishing systems are the best choice to protect data centres, the latest technological findings show that in very rare cases computers and HDDs can face problems after the extinguishing process has been triggered. These problems may range from automatic shutdown of an HDD with no damage after restart to more severe disturbances. Research has shown that the main cause of these problems was the high noise level caused by the discharge of the agent during the extinguishing process. 

To address this issue, silent extinguishing technologies have been developed specifically for data centres and server rooms. This enables reliable protection of IT operations and minimises the risk of business interruptions following a fire extinguishing system discharge. 

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Experience and expertise

The value of the global data centre market was estimated at $187.35 billion in 2020 with growth projections suggesting it will reach $517.17 billion by 2030. Given the fundamental role that data centres play in modern business and life in general, minimising disruption has to be a prime concern. To ensure the highest possible fire safety, it is important to control the interfaces and use the latest scientific findings for the best solution. Having a complete fire safety system from a single supplier with extensive experience in data centre applications can provide the optimum solution in terms of detection, alarming, control and extinguishing.