Information Technology Reference
In-Depth Information
Power is consumed by the following:
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Cooling
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Servers
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Storage
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Network
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Conversion and lighting
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Data Center Cooling
Devices in the data center produce variable amounts of heat depending on the device load.
Heat overtime decreases the reliability of the data center devices. Cooling is used to con-
trol the temperature and humidity of the devices, and it is applied to zones, racks, or indi-
vidual devices.
Environmental conditions need to be considered and measured by using probes to meas-
ure temperature changes, hot spots, and relative humidity.
A major issue with high-density computing is overheating. There are more hot spots, and
therefore more heat overall is produced. The increase in heat and humidity threatens
equipment life spans. Computing power and memory requirements demand more power
and thus generate more heat output. Space-saving servers increase the server density pos-
sible in a rack, but keep in mind that density = heat. It might not be a big deal for one
chassis at 3 kilowatt (kW), but with five or six servers per rack, the heat output increases
to 20 kW. In addition, humidity levels can affect static electricity in the data center. So, it
is recommended that relative humidity level be in the range of 40 percent to 55 percent.
High levels of static electricity can cause damage to data center equipment.
Proper airflow is required to reduce the amount of heat generated by the high-density
equipment. Sufficient cooling equipment must be available to produce acceptable temper-
atures within the data center. The cabinets and racks should be arranged in the data center
with an alternating pattern of “cold” and “hot” aisles. The cold aisle should have equip-
ment arranged face to face, and the hot aisle should have equipment arranged back to
back. In the cold aisle, there should be perforated floor tiles drawing cold air from the
floor into the face of the equipment. This cold air passes through the equipment and
flushes out the back into the hot aisle. The hot aisle does not have any perforated tiles,
and this design prevents the hot air from mixing with the cold air.
Figure 4-5 illustrates the alternating pattern of cold and hot aisles along with airflow.
For equipment that does not exhaust heat to the rear, here are some other cooling techniques:
Block unnecessary air escapes to increase airflow.
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Increase the height of the raised floor.
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Spread out equipment into unused racks.
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Use open racks rather than cabinets where security is not a concern.
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