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September 2011: Automatic Fire Protection for Automated Tape Libraries / Silos in Information Technology Equipment Rooms

They go by many names - computer rooms, server rooms, main distribution frame (MDF) rooms, data centers, electronic data processing (EDP) centers, information technology (IT) equipment rooms, etc.; but, no matter what you call them, these areas house expensive IT equipment and operations that can be critical to the daily operations for an industrial facility. In many cases, these areas / equipment are the lifeblood of a company.

While there is normally no doubt of the need for automatic fire protection for these rooms, an often overlooked facet is the protection of some of the equipment enclosures themselves. Many data centers still make use of plastic tapes for data storage. It is the best loss control advice to keep IT equipment separate from tape storage, whether it is in open/closed racks or in automated tape library (ATL) and automated information storage system (AISS) units. The IT equipment and tape storage rooms should be separated by preferably, minimum 1 hr. rated construction. Automatic sprinkler and smoke detection systems should be provided in each area and should be properly designed. The need for secondary fire protection systems (i.e., gaseous extinguishing systems) in computer rooms and/or below raised floors is dependent on the loss exposure and criticality of the equipment/operation to the site/company.

In some cases, AISS units must be located in the main computer room. Although not ideal, this is tolerable if the interior of AISS enclosure is protected by an automatic fire protection system, or if the unit is small enough not to warrant any automatic protection. Older AISS units included large silos that could be arranged in series/parallel. These massive units can store thousands of tapes and occupy a considerable amount of floor space. Newer, modular ATL units are cube shaped and can take up just as much floor space as the silos.

NFPA 75, Standard for the Protection of Information Technology Equipment, recommends automatic fire protection inside ATL units with an aggregate storage capacity greater than 27 cu. ft. The standard specifically states:

"8.1.4 Automated information storage system (AISS) units containing combustible media with an aggregate storage capacity of more than 0.76 cu. m (27 cu. ft.) shall be protected within each unit by an automatic sprinkler system or a gaseous agent extinguishing system with extended discharge."

If a gaseous extinguishing system is to be installed, it should be installed in accordance with NFPA 2001, Standard on Clean Agent Fire Extinguishing Systems or NFPA 12, Standard on Carbon Dioxide Extinguishing Systems depending on the system type chosen.

Smaller automated tape, cassette, or optical disk libraries (i.e., not of "walk-in" size) should be evaluated on a case-by-case basis, based on equipment value and value of data stored, to determine whether fixed automatic gaseous extinguishing system protection can be cost-effectively provided. In some cases, an acceptable approach may be to install internal smoke detectors within the units and interlocking them to de-energize the unit upon activation.

FM Global Property Loss Prevention Data Sheet 5-32, Electronic Data Processing Systems, further indicates that automatic sprinkler protection, installed either inside or outside the AISS enclosure, is usually not an acceptable alternative to protect the unit and contents (for property loss control purposes) unless a fire involving the unit presents a low loss expectancy and there is little to no business interruption potential due to the destruction of any of the tapes/cassettes.

Fire detection for an extinguishing system discharging directly into the equipment cabinet should preferably use photoelectric or a combination of photoelectric and ionization smoke detectors located in the cabinet (if space permits) or air sampling-type detectors located out-of-cabinet which can sample the air in the cabinet. If the enclosure is not completely airtight and smoke can easily migrate out, then the use of smoke detectors located in the room housing the equipment is tolerable to actuate the extinguishing system.

Ideally, power to the AISS should be interlocked to shut off if smoke is detected inside the unit.

For equipment that cannot be de-energized upon extinguishing system discharge due to process control, safety, or other considerations, FM Global recommends that the required agent concentrations should be held for a period of 10 minutes. For either the 1 minute or the 10 minute holding time, an extended discharge system (as recommended by NFPA 75) may help maintain the needed concentrations despite the presence of some significant openings in the equipment enclosure.

Tape virtualization may one day eliminate the need for plastic tape storage/use in data centers. Until this time comes, protecting the high valued IT equipment from an exposure fire involving plastic tapes (either in racks/shelves or in ATL's/silos) should be a high priority for IT Management. A typical fire scenario for an unprotected AISS unit is as follows:

"An unprotected fire originating inside a large AISS enclosure would likely be shielded from the room's fire protection system (automatic sprinklers or gaseous extinguishing system, if provided) and would be able to spread throughout all interconnected modules/units. If provided and adequately designed/maintained, the room fire protection system would eventually operate and prevent fire spread beyond the unit involved, but all of the attached modules may be destroyed and substantial smoke and water damage could affect the entire room. Costly repairs/replacement of sensitive EDP equipment would be needed, and site operations, which the computer room supports, may be halted until disaster recovery operations could be established."

The above scenario could be a catastrophic loss at some facilities.

If you would like further information regarding automatic fire protection for automated tape libraries / silos in data centers, please contact Risk Logic Inc.