R&M Data Center Handbook

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In general, air-conditioning units can be placed inside or outside a data center. Inside use is better for rack-based
cooling or specific cooling of hot spots in a server room. Operational costs are lowered and the associated noise
stays inside the room. Units are also protected from unauthorized access and the protective wall is not weakened
by additional openings for ventilation slides. The advantages of outside use are that service technicians do not
need to enter the room for maintenance work, the air-conditioning units require no extra space in the data center
and the fire load is not increased by the air-conditioning system. Fresh air supply can generally be achieved
without additional costs.
In most cases, redundancy in accordance with Tier III and IV (see section 2.2.1.) is only required for airconditioning
units on walls and ceilings that have a rather low cooling capacity. When higher capacities and thus
stand-alone units are required, a "N+1 redundancy" in accordance with Tier II should be established, which leaves
a number of units in continuous operation while an additional unit acts as redundancy (reserve).
In order to establish and maintain the recommended relative humidity range of 40% to 60%, the air-conditioning
units should feature both air humidifiers and dehumidifiers. A safe bet is to opt for a system certified by Eurovent
(the interest group of European manufacturers of ventilation and air-conditioning systems). For cooling hot spots
in data centers, the use of liquid-cooling packages is also an option. These packages extract the emitted heat/hot
air along the entire length of the cabinet by means of redundant, high-performance fans, discharging it via an air
and water heat exchanger into a cold water network or a cooler.
Dust Risk
Dust is the natural enemy of sensitive IT systems and does not belong in secure data centers. Fine dust particles
can reduce the life cycle of ventilators and other electronic units drastically. One main source of dust is
maintenance work and staff – any intrusion into secured data centers must be avoided. An intelligent IT room
security system is absolutely dust-free. The dust-free policy also applies to extension or upgrade work. The dusttightness
in place should comply with the specifications in EN 60529, and fulfill IP56 with characteristic 1 (see
water risk) in order to avoid any unpleasant surprises at a later stage.
Unauthorized Access Risk
The data center is one of the most sensitive areas in a company. It is critical that only
authorized persons have access, and that every data center access is documented. A
study of the International Computer Security Association (ICSA) showed that internal
attacks on IT systems are more frequent than external ones. Protection of the data center
must therefore first meet all requirements in terms of protection against unauthorized
access, sabotage and espionage, and also ensure that specifically authorized persons
can only enter the rooms they need to perform their defined tasks. Burglary protection in
accordance with EN 1627 with resistance class III (RCIII) is easily implemented. All
processes are to be monitored and recorded in accordance with the relevant documenttation
and logging regulations.
If possible, the air conditioning system and electrical equipment should be physically separated from the servers
so that they can be serviced from the outside. For access control purposes, biometric or standard access control
solutions can be installed or a combination of the two. Biometric systems in combination with magnetic card
scanners enhance the security level considerably. Most of all, the access control solution installed should fulfill the
specific requirements of the operator. The highest level of security can be guaranteed by the new vein recognition
technology. Its high precision and thus critical advantage stands out in its false acceptance rate of less than
0.00008 percent and a false rejection rate of only 0.01 percent. Moreover, it ensures highly hygienic handling,
since operating the device does not require direct contact.
By using video surveillance systems with image sensors in CCD and CMOS technology, up to 1000 cameras can
be managed with the matching software, regardless of the manufacturer. Video surveillance systems provide
transparency, monitoring and reliability in data centers. Advanced video management technology enables modern
surveillance systems to manage and record alarm situations. For images to be analyzed and used as evidence,
an intelligent system must provide the proper interfaces and processing possibilities.
Explosion Risk
The risk of terror attacks or other catastrophes which could trigger an explosion must be factored in right from the
start when planning a highly available security room concept. Modern, certified server rooms need to undergo an
explosion test in accordance with the SEAP standard. High-security modular server rooms are built with pressureresilient
wall panels to resist heavy explosions, protecting valuable IT systems from irreparable damage. IT
systems need also be protected against debris and vandalism, to ensure real all-round protection.
Page 18 of 156 © 08/2011 Reichle & De-Massari AG R&M Data Center Handbook V2.0