Site Preparation Guide, Second Edition - HP Integrity cx2620 Server

• Filtration at 35–55 percent spot efficiency per American Society of Heating, Refrigerating,
and Air-Conditioning Engineers (ASHRAE)
• Air conditioning heat load limits at 80 percent of total heating, ventilation and air conditioning
(HVAC) capacity
Airflow
An incorrect public perception exists that cool, ambient air is consistent throughout a datacenter.
That is, if the temperature of the room is measured at 20° C (68°F), then the equipment should
be stable. In reality, microclimates can exist in various parts of the room such that generated heat
in the equipment might not efficiently make its way out. Microclimates are difficult to detect
and prove; therefore, prevent microclimates by encouraging a high rate of airflow from source
to intake of HVAC and uniform distribution of the heated air. Underflow blockages, such as
cabling and piping, can disrupt the airflow predictability. Improperly positioned floor vent tiles
or equipment can create air dams and decrease airflow. Follow these general precautions to
ensure proper airflow:
• Use a heat load to 80 percent of total HVAC capacity (maintain a thermal safety margin).
• Place vented floor tiles only in heat load areas.
• Do not place vented floor tiles within two floor tiles of HVAC (thermal short circuit).
• Do not place heat loads closer than two floor tiles of HVAC.
• Be sure the maximum distance from the HVAC to the heat load is less than 75 feet (22.86
m).
• Seal all cable openings (unsealed openings create a loss of static air pressure).
• Lay out equipment aisles parallel to airflow, not perpendicular to it.
• Concentrate high-density heat loads in a tightly controlled area. High-density loads are
equivalent to one cabinet of 3 kilowatts or more.
• Maintain airspeed through vent tiles at more than 500 feet per minute (152.4 meters per
minute), but at less than 700 feet per minute (213.36 meters per minute) for high-density
cooling.
Equipment Orientation
Data center equipment orientation or heat load must encourage sufficient airflow. If exhausted
heat must move over or around a cabinet, air vortexes might be created, resulting in airflow
inefficiency throughout the data center and inside the equipment. Equipment might develop
internal hot spots, resulting in sluggish performance or even system failure.
Rather than designing a layout to maximize a planning grid worksheet whitespace, consider
creating “hot” and “cold” aisles. In a hot aisle, equipment is oriented so that exhaust vents face
other exhaust vents. In a cold aisle, intake vents face other intake vents. Place vent tiles in the
cold aisles, with few to no vent tiles in the hot aisle. Position equipment in parallel to encourage
the lowest air resistance and turbulences. Consider the following when determining equipment
orientation:
• Orient equipment in parallel to airflow.
• Place cabling in such a way as to aid airflow rather than impede it.
• Layout equipment to form hot and cold aisles.
• Use vent tiles to control airflow in heat load areas.
• Place vent tiles in cold aisles.
• Place higher heat load devices at floor level.
Electrostatic Discharge
Computer equipment is increasing in processor and memory density even as size continues to
decrease. These smaller, more densely packed pieces of equipment are at greater risk to damage
from electrostatic discharge (ESD). ESD created by the human body is consistent at approximately
30 General Site Preparation Guidelines