Antecedentes entre la música y yo

M.T.AREITIO and J.AREITIO Networks & Systems, Bilbao, Spain Abstract

This paper analyzes new issues for fire protection in modern computer networks centres. Fire is the single most feared physical hazard that can strike a information processing facility. Fortunately major fires are rare occurrences due to the high level of cleanliness and the controlled environment which are to be found within the majority of installations.

However, there are no completely non-combustible computers. Circuits boards, resistors, network interface cards, capacitors, transformers, wiring and other components can provide fuel for a fire. The risk of fire is increased when paper and plastic items are introduced into the computer networks room. It is essential that, should a fire start, it is detected and then extinguished rapidly in order that total disaster is avoided. This paper introduces a specific strategy in order to prevent fire in computer networks centres.

Keywords: Computer networks, detection, extinguishment system, fire protection, prevention, stategies.

1 Initial aspects

A computer networks centre can only function when all environmental controls and services are reliable and continuous. From a security standpoint, this paper shows how the environment is becoming increasingly important. For example, the situation could arise where an access control system, installed at considerable expense to prevent unauthorized access to vandals, burglars, etc was fully functioning but the entire computer networks centre was put out of action by a fire.

There are three keywords that come up in discussions of computer networks security:

vulnerabilities, threats and countermeasures. A vulnerability is a point where a system is susceptible to attack. A threat is a possible danger to the system, the

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danger might be an event (a fire, a flood,…), a person (a spy,…), a thing (a faulty piece of equipment) that might exploit a vulnerability of the system. Techniques for protecting your system are called countermeasures. Computer networks security is concerned with identifying vulnerabilities in systems and in protecting against threats to those systems.

Every computer networks system is vulnerable to attack. Security policies and products may reduce the likelihood that an attack will actually be able to penetrate your system’s defenses, or they may require an intruder to invest so much time and so many resources that it’s just not worth it, but there’s no such thing as a completely secure system. Computer networks are very vulnerable to natural disaters and to environmental threats. Disasters such as fire can wreck your computer network and destroy your data.

Natural and physical threats are the threats that imperil every physical plant and piece of equipment: fires, power failures, and other disasters. You can’t always prevent such disaters, but you can find out quickly if one occurs (with fire alarms, temperature gauges, and surge protectors). You can minimize the chance that the damage will be severe (e.g., with certain types of sprinkler systems). You can institute policies that guard against hazards posing special dangers to computers (like smoking). You can also plan for disater (by backing up critical data off-site and by arranging for the use of a backup system (alternative computers network) that can be used if an emergency does occur).

Despite advances in computer security and communications security, physical security remains vitally important component of your total security plan. Physical security measures are tangible defenses that you can take to protect your facility, equipment, and information from theft, tampering, careless misuse, and natural disasters. In some ways, physical security is the easiest and the most rewarding type of security. It’s very visible and reassuring. It’s a tangible signal to employees and clients that you take security seriously. Building, computers room, computers, and media locks provide an important outer, physical perimeter of security. Within this perimeter, access controls and other types of security provide finer-grained protection of information.

Some important considerations:

1. Install smoke detectors near your equipment and check them periodically.

2. Keep fire extinguishers in and near your computer networks rooms, and be sure everyone knows they’re there.

3. Enforce no-smoking policies, these are also important to controlling smoke, another hazard to computer networks.

4. Consider using specially formulated gases such as Argonite, which smothers fires and avoids the danger of water damage.

2 Prevention system

The facility should be constructed from fire-resistant materials, including floor-to-ceiling, fire-resistant barriers in order that the facility is completely separate from, for example, office areas. This is particularly important as such external areas normally receive a far lower level of fire protection than the computers room. A large proportion of recorded computer room fires started outside and burnt their way into the computers room. Items such as furniture, decorations, etc. should be fire-resistant. Strict limitations should be placed on the amount of combustible material which is unavoidably introduced such a manuals, books, stationery, cleaning fluids, aerosols, etc…

The computers room (i.e. server farm) must obviously be designated as a non-smoking area and all food and drink must be excluded. At the same time, acceptable rest and refreshment areas should be provided for staff. Regulations must be introduced for the

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removal of rubbish; the underfloor void must be cleaned at least quarterly. Despite the introduction of preventative measures, staff awareness and good housekeeping practices can achieve much in this area.

3 Detection system

In the event of a fire outbreak within the facility, the early detection of the fire is essential to prevent its spread and the resulting severe damage. A fire may be detected by one of the following methods:

1. Observation (artificial, human,…).

2. Heat Detectors.

3. Smoke Detectors.

4. Combustion Detectors.

The detection system must be linked to a central system which will sound an alarm and activate the extinguishing system. The reliance on human intervention to observe the outbreak of fire, possibly out of normal working hours, and then to raise the alarm should be ruled out as far as a computer installation in concerned. Automatic detectors must be installed. Their purposes could be:

1. To alert personnel to the fire in order that they could tackle it with portable extinguishers if safe to do so, prior to the operation of an automatic extinguishing system.

2. To summon the fire brigade.

3. To additionally initiate controls of special extinguishing systems such as air conditioning closedown, door closing, etc.

The usual method of detection is by the use of smoke detectors. The sensitivity of this type of detector is such that low levels of smoke particles are rapidly dispersed long before flames become visible or a significant temperature rise has occurred.

Extinguishment at an early stage is able to take place. The system should be designed in such a way that more than one detector must confirm the presence of smoke prior to extinguihment release. In this way detection system fault can be avoided. Specialist advise should be sought for detector installation, but the following guidelines should be observed:

1. The efficiency of the detector could be considerably reduced if it is sited within the airflow of an air conditioning unit. Smoke could be diffused to such a level that the fire would only be detected once it had grown to considerably proportions.

2. The detector should be capable of detecting different types of smoke. For example, smoke produced by burning plastic, often used in wiring insulation, may not be detected.

3. Smoke detectors should be installed in the periphery of the computers room in addition to within it. As previously discussed, a fire which starts outside the computers room can dangerously develop, so it is advisable to install a zone of detectors at least within the areas inmediately surrounding the facility. Such detectors should form part of the

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corporate fire protection system but there must be an indication of the special nature of a detected fire in these areas, prompting special action.

4. Smoke detectors should also be fitted in the underfloor void and within air conditioning ducts.

It should be noted that the activation of the detection system can have no benefit unless a response take place. When the system is planned, the detector zone should be kept as small as possible to minimize the damage a fire would cause. More important is the level of response to the alarm which may mean the different between a small fire being quickly extinguished and a major conflagration.

4 Extinguishment system

The agents used for fire suppression within the computing environment are:

1. Carbon Dioxide (CO2).

2. Halon Compounds.

3. Water. It’s not a good fire protector for computer systems rooms. In fact, more destruction has been done by sprinkler systems trying to stop fires in computers rooms than by fires themselves.

4. Argonite (50% Ar-50% N2). It’s a clean agent. (No Observe Adverse Effect Level=40% Ozone Deplection Potential=Global Warning Potential=0).

5. Inergen (52%-N2, 40%-Ar, 8%-CO2). It’s a clean agent.

6. Argon (100%-Ar). It’s a clean agent.

During the past decade the use of CO2 has generally been discontinued as it depends on the displacement of air to inhibit combustion and concentrations of up to 46% may be required. Used in occupied areas, the hazard of suffocating personnel would be present.

However, small capacity, CO2 extinguishers are in use although concern has been expressed regarding the thermal shock effect produced by the gas which could cause chips and circuit boards to crack. CO2 has been replaced by Halon as the premise gas extinguishing agent because:

1. Halon interrupts the oxidation chain reaction, thus extinguishing the fire.

2. A concentration of only 6% is required, at which level it can be considered to be non-toxic.

3. Halon is non-conductive, non-corrosive and, when discharged, leaves no messy residue to clean up.

4. Halon can operate via an automatic release system, preferably equipped with a manual release override.

Halon compounds used in extinguishing systems are either Halon 1211 (Bromochlorodifluoromethane, or BCF) or Halon 1301 (Bromotrifluoromethane, or BTM). The differing physical properties of these two distate that 1301 system is suitable for fixed installation and 1211 more appropiate for portable extinguishers. A Halon 1301 system should be considered where there is:

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1. The need to reduce equipment fire damage by way of early automatic fire extinguishment.

2. A critical need to facilitate a swift return to service of the equipment after the fire.

3. A critical need to protect data being processed.

4. The need to protect void spaces not suitable for water sprinkler protection.

It is argued that water sprinkler systems are more effective in extinguishing fire than the other available means. It is agree that the majority of Halon systems release the gas only once, or at most twice, and this may not be sufficient to put out a deepseated fire. In addition, unless the system receives on-going expert attention, correct Halon concentrations are difficult to maintain. To ensure the effectiveness of a Halon system all ducting, doors and windows must be sealed, as, operating under pressure, the gas may dissipate rendering it ineffective and causing the fire to re-ignite. Despite all such precations a door or window left open could have the same effect, as could a fire which burnt its way into the computer networks room from outside. The Halon will escape through the entrance made by the fire. It is further argued that should the Halon system fail to supress the fire, more damage is inflicted by the indiscriminate use of fire hoses by the fire brigade.

Some organizations have banned the use of any other systems but water sprinklers.

Sprinkler heads of the ’wet’ type i.e. when water is held back by a heat activated valve at the head itself, have an extremely low failure rate and the introduction of ’dry’ pipes, water retained in a remote tanks, have further contributed to their reliability. However, the concer of water coming into contact with electrical equipment may rule out their usage. Automatic equipment power-down should precede the activation of sprinklers. It is often the case that the surrounding areas, officies and storage, are protected by spriklers and the computer networks room itself is equipped with Halon.

A growing trend is the use of foam extinguishants. Previously widely used in aviation, marine and petrochemical industries, foam, particularly of the high expansion type, has now been used by a number of financial institutions. A use for a foam system could be for the protection of the underfloor void which could take place separately from the main extinguishing system, thus avoiding a total discharge situation.

Portable extinguishers must be made available both within and outside the computers facility. Those within the facility should be either Halon 1211 or CO2. It must be emphasized that dry chemical extinguishers should never be used in the computers room as the extinguishing agent contains corrosive substances which will attack electronic equipment. An inspection should take place, at least monthly, to ensure that the appliances are in their correct positions, have not been discharged or lost pressure. All staff should receive adequate training not only in the operation of fire extinguishers, but also which extinguisher to use.

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5 Final considerations

A defense against fire is careful placement of a computing facility. A windowless location with fire-resistant access doors and nonflammable full-height walls can prevent a fire from spreading from adjacent areas to the computing room. With a fire-and smoke- resistant facility, personnel merely shut down the system and leave, perhaps carrying out the most important media.

Fire prevention is quite effective, especially since most computer goods are not especially flammable. Advance planning, reinforced with simulation drills, can help to make good use of the small amount of time available before evacuation is necesary.

6 Bibliography

1. Areitio, J. and Areitio, M.T. (1994) Aplicación multidimensional de la seguridad informática operacional. Revista Española de Electrónica, Barcelona, No. 481 pp. 43–48.

2. DataPro (1992) Network Services, McGraw-Hill, New York.

3. Ferry, T.S. (1988) Modern Accident Investigation and Analysis, (ed. T.S.Ferry), U.S.

4. National Fire Protection Association (1991) Fire Protection Guide on Hazardous Materials.

NFPA, U.S.

5. National Fire Protection Association (1986) Fire Protection Handbook. NFPA, U.S.

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