HP 3PAR StoreServ 7200 2-node HP 3PAR StoreServ 7000 Storage Site Planning Man - Page 20

normally required to replace moisture removed during the cooling process. The relative humidity for a subsystem equipment room should be set at 40%. This level is sufficient to suppress electromagnetic charge buildup, and low enough to avoid the risk of corrosion and condensation. To avoid air contamination from the humidifier, water treatment may be necessary in areas with high mineral content. Air Supply and Flow The air flow capacity of the facility where the storage systems are installed needs to be sufficient to remove the heat generated by the equipment. In addition, the air handlers must provide the airflow volume required by the units being cooled. To ensure this airflow, the facility must have a positive air pressure underneath the floor (if the facility has raised floors). When conditions within the computer room are changed (new units are added, the computer system is moved, and so on), airflow checks should be made. The amount of outside (composition) air should be kept to the minimum needed to create a slight positive pressure within the room, and it should not exceed industry recommendations of 0.3 cubic meters/minute (10 cubic feet/minute) per person stationed in the equipment room. While recommendations for outside air in comfort air conditioning are 10-15% of the airflow, the computer room environment is cleaner and operates more efficiently if outside air is kept below 1 percent of the airflow. Cooling/heating and humidification needs are reduced, and a minimum of contaminated building air is introduced into the installation area. Air Cleanliness Air contaminants can cause equipment malfunction and can damage storage systems. It is essential that steps be taken to prevent air contaminants, such as metal particles, solvent vapors, corrosive gases, soot, airborne fibers, or salt, from entering or being generated within the server room environment. A high-efficiency air filter should be employed on each air inlet for outside air to stop dust at the point of entry to the installation site. Special additional filtering is necessary where the environment is exposed to salt air, corrosive gases, or unusual dust/dirt conditions. Electronic equipment is sensitive to air contaminants such as the following: • Excessive amounts of soot particles • Condensate particulates such as carbonates • Concrete particulates from unsealed concrete • Metal flakes or filings, such as those produced by sawing, filing, or drilling • Floor-cleaning solutions with high ammonia content. • Deteriorating/decomposing building materials, including floor tiles, fabrics, sheetrock, insulation, and acoustical tiles • Pollutants generated by any servicing performed in and around the computer room • Paper chaff, dust, and toners from printers within the computer room • Processing chemicals from reproduction equipment such as microfiche processors. In electronic equipment, contaminants cause connector contact and motor-bearing degradation. They also cause electrical leakage, shorting paths between integrated circuit leads and between printed wiring traces on printed circuit boards. Air supplied to and circulated within the server room and plenums underneath the floor should ideally pass through mechanical or electrostatic filters. HVAC ducts and plenums and sub-floor areas, including cable raceway openings (where used), should be kept clean. All unused cables, hardware, and debris should be removed from the area underneath the floor to avoid becoming dust/dirt traps or potential sources of rust. 20 Structural/Environmental Considerations