Emelie Andrén Meiton, Product Line Manager at Siemens Building Technologies, explains how the company’s technology is used to protect vital data centres
In the modern world data is at the heart of commerce, with very few businesses which are not in some way reliant on data. There are an estimated 30 million servers worldwide processing ever increasing quantities of video, voice and data through a global network of several billion devices. It is therefore not surprising that business continuity and disaster recovery plans often originate from a corporate data centre position since an incident here has such far-reaching consequences. Central to this is the provision of effective safety and security, including the protection of data from the threat of fire.
One of the most likely causes of a catastrophic failure is fire yet its threat is often underestimated. Housing as they do such sensitive, vital information and systems essential to the survival of their clients, data centres present a greater need for absolute protection whilst paradoxically demonstrating an enhanced level of fire risk. The electrical power and extensive cabling that drive the computing systems provide a constant source of potential ignition, particularly under the raised floors, while the many thousands of plastic components supply a plentiful source of combustible materials. Given that an estimated 80 percent of fires are caused by electrical faults, the role of effective, intelligent and safe distribution of power is itself a vital consideration in safety terms.
Cooling requirements impact on fire safety
Both preventive and active fire protection is therefore particularly relevant in such vulnerable locations. The newer high-performance equipment, such as multi-processor servers and high-speed communications switches are raising rack densities well above 30 kW (equivalent to the drive output of an electric car). In ever more densely packed layouts, today’s servers necessitate air-cooling up to 8600 watts/m2. To help put this into context, on a cloudless day in mid-Europe, the sun will typically generate 700 watts per square metre. The equivalent of a cooling power of 8400 watts/m2 would therefore be like lowering the temperature from 12 suns burning down on one square metre. The resulting higher air exchange from cooling will partly remove any smoke with the airflow, making early detection by traditional systems even more difficult, as well as increasing the risk of the fast spread of fire to other areas. Even a smouldering fire without flames can damage hardware through sooting, corrosion and toxic gases. The time between the initial outbreak of fire and its successful extinguishing after detection, is the critical factor when attempting to prevent operational failure of a data centre.
The earliest possible warning
Given the susceptibility of data centers to the threat of fire, even in its early incipient stages, detecting it at the earliest possible point is the objective. It is generally accepted that aspirating smoke detection (ASD) is one of the technologies which provides the earliest detection of the incipient stages of combustion. ASD is therefore very widely used to protect IT and telecommunications facilities – the applications for which it was originally developed – protecting the highly ventilated atmosphere which typifies the data centre environment.
Aspirating smoke detection systems can detect smoke before it is even visible to the human eye. The systems generally consist of a network of independent pipes with one or more sampling apertures that actively draw air into a highly sensitive smoke-sensing chamber. There, the sampled air is precisely and accurately analysed by a scattered-light detector for smoke particles. If smoke particles beyond a pre-set threshold are detected, the system triggers an immediate alarm. In that way, a timely warning is given – along with the opportunity to fully investigate the cause of the alarm. The most appropriate response can then be initiated to stop the fire gaining a hold and thus prevent injury, damage and disruption to business.
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 – without external input. 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.
Intervention and extinguishing
Shutting down equipment at the earliest indication of fire will stop even corrosive combustion gases developing further. However, in order to prevent false alarms, standards still often require two separate detectors to sound an alarm before the extinguishing system is activated – a single detector causes the system to go into a state of pre-alarm, and only if the alarm is reconfirmed the extinguishing agent will be released. Thanks to modern technology though and to the high detection reliability of today’s point type detectors and ASD, false alarms can be excluded, even when using just one detector, without an alarm verification system.
The method of delivering the extinguishing agent and selecting the correct agent for the given application is a very important factor in optimising protection. In critical applications, a dry extinguishing system is essential because of the sensitivity of the IT infrastructure. Water is generally not used as an extinguishing agent in data centres, the only exception being in generator rooms in which combined gas/water solutions are used because of the thermal risk. Two types of gas extinguishing systems are especially suited to data centres: Chemical extinguishing agent systems and inert gas systems. The latter tend to be employed in medium to large-sized data centres while chemical agents are used in small to medium-sized data centres.
Since the server rooms are the raison d’etre of a data centre, special solutions have to be employed even on the hardware side of extinguishing: recent studies have shown that the noise of conventional gas extinguishing systems could affect the performance of the hard disk drives. That is why today silent extinguishing systems with purpose-built silent nozzles are the solutions of choice for data centre extinguishing, with both natural gas and chemical agents.
In other critical applications such as generator rooms, uninterrupted power supply (UPS) systems ensure continuity in case of power cuts. As alluded to above, in such situations extinguishing agents are available which combine nitrogen and water – the excellent extinguishing characteristics of nitrogen with the addition of water mist to cool down hot surfaces, thereby putting out the fire faster and avoiding re-ignition.
The seamless interaction between fire detection and extinguishing is a basic requirement for ensuring effective fire safety and minimum downtime. Analyses by leading independent testing institutions in fire protection and security worldwide consistently highlight that the prime cause for fire safety system failure is the interface between detection, alarming, control and extinguishing. Early, reliable detection of a fire and the initiation of appropriate extinguishing measures are critical factors in an effective protection concept. Fire detection, evacuation and extinguishing systems must therefore be fully compatible with each other. Systems with real interoperability from a single source are therefore the preferable option in such a mission critical environment as a data centre, requiring a partner with competence not only in the detection and extinguishing technologies but in the interoperability processes themselves.
Electronic security and safety solutions can help protect a data centre and in doing so protect an organisation’s application availability, its confidentiality, its integrity and, ultimately, its ability to function. Integration of security and safety measures is one of the prime methods of enhancing business continuity through protection of business-critical data. Central management of operational systems provides a more efficient and dynamic use of resources, focusing them when and where they are needed. Fire safety and security can be integrated through danger management stations. This allows for centralised supervision and alarm handling from a number of different sources, including fire detection, video surveillance, access control and intrusion detection.
The benefits of integrating fire safety and security are numerous: video surveillance allows the danger zone to be viewed immediately, offering a visual means of verifying and assessing the situation; integrated access control provides monitoring of escape routes and the means to quickly open or close doors, an important part of the evacuation process; integrated intrusion detection means that data and electronic equipment are protected not only from the threat of fire but also against unobserved theft or sabotage. All of this through a single, centralised station which guides personnel through the step-by-step processes to be followed in the event of an incident. This integrated view of what is happening not only helps to resolve an incident but also provides the capability to learn from incidents which is crucial in enabling process adaptation in the very dynamic risk landscapes which characterise today’s business environments. Although safety and security are not a direct part of IT operations, they definitely help to ensure the business continuity environment of a data centre.
Also building automation and control systems can be integrated to enable control of heating, ventilation, air conditioning, lighting and blinds to optimise energy efficiency – a vital consideration when growth in data centre infrastructure requirements suggests power needs may necessitate the construction of 10 to 15 new power plants over the next decade in each high density region.
An example of how an integrated approach to safety and security can optimise protection is illustrated by Safe Host, a Swiss data centre comprising a six story building, five of which are occupied by approximately 12,000 servers and storage devices containing the data of more than 140 customers. The expansion of the data center was driven by demand – the facility being equipped floor by floor with the latest technology, as and when required. For this reason, Safe Host’s building now contains different generations of fire detection and extinguishing equipment. Some floors use detectors and control panels from Siemens older AlgoRex line, while most are equipped with devices from Siemens’ current Sinteso family. All security devices are managed using a central Siemens’ management station that collects information from more than 2,800 data points and visualises them on 60 graphical displays of all the floors.
The Safe Host building is today divided into 350 fire detection zones and uses no fewer than 830 highly sensitive fire detectors from Siemens’ Sinteso and AlgoRex families. They are supported by approximately 30 aspirating smoke detectors (ASDs) that continuously analyse air in the rooms for smoke particles. All detectors throughout the Safe Host building are connected to four fire control panels, supplemented by floor repeater displays. Some 50 manual call points are also installed at strategic locations and in an emergency, 65 alarm sounders ensure that the building is evacuated effectively.
As already stated. solutions using water or water mist are not recommended in data centre applications. The moisture could potentially cause more damage to the servers’ sensitive electronics than the fire itself. For this reason, Safe Host uses a Sinorix gas extinguishing system. If the fire detectors confirm a fire, the system automatically triggers the extinguishing process. Valves on the gas cylinders in the basement of the building are opened and nitrogen, as an inert natural gas, flows through a network of pipes to wherever it is needed. There, the nitrogen displaces oxygen, depriving the fire of one of its essential components. Once the oxygen level is reduced from 20.9% to under 14% any fire is extinguished and re-ignition is impossible. This all happens in a matter of seconds and it is an effective way to extinguish both open and smouldering fires. Nitrogen also poses zero risks to human health or well-being.