Oracle Exalogic Elastic Cloud, Руководство пользователя

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• Optimal range helps protect computer systems from corrosion problems
associated with high humidity levels.
• Optimal range provides the greatest operating time buffer in the event of air
conditioner control failure.
• This range helps avoid failures or temporary malfunctions caused by intermittent
interference from static discharges that may occur when relative humidity is too
low.
Note:
Electrostatic discharge (ESD) is easily generated, and hard to dissipate in areas
of low relative humidity, such as below 35 percent. ESD becomes critical when
humidity drops below 30 percent. It is not difficult to maintain humidity in a
data center because of the high-efficiency vapor barrier and low rate of air
changes normally present.
2.6 Ventilation and Cooling Requirements
Always provide adequate space in front of and behind the rack to allow for proper
ventilation. Do not obstruct the front or rear of the rack with equipment or objects that
might prevent air from flowing through the rack. Rack-mountable servers and
equipment typically draw cool air in through the front of the rack and let warm air out
the rear of the rack. There is no air flow requirement for the left and right sides due to
front-to-back cooling.
If the rack is not completely filled with components, then cover the empty sections
with filler panels. Gaps between components can adversely affect air flow and cooling
within the rack.
Relative humidity is the percentage of the total water vapor that can exist in the air
without condensing, and is inversely proportional to air temperature. Humidity goes
down when the temperature rises, and goes up when the temperature drops. For
example, air with a relative humidity of 45 percent at a temperature of 24 degrees
Celsius (75 degrees Fahrenheit) has a relative humidity of 65 percent at a temperature
of 18 degrees Celsius (64 degrees Fahrenheit). As the temperature drops, the relative
humidity rises to more than 65 percent, and water droplets are formed.
Air conditioning facilities usually do not precisely monitor or control temperature and
humidity throughout an entire computer room. Generally, monitoring is done at
individual points corresponding to multiple exhaust vents in the main unit, and other
units in the room. Special consideration should be paid to humidity when using
underfloor ventilation. When underfloor ventilation is used, monitoring is done at
each point close to an exhaust vent. Distribution of the temperature and humidity
across the entire room is uneven.
Exalogic machines have been designed to function while mounted in a natural
convection air flow. The following requirements must be followed to meet the
environmental specification:
• Ensure there is adequate air flow through the server.
• Ensure the server has front-to-back cooling. The air inlet is at the front of the
server, and the air is let out the rear.
Ventilation and Cooling Requirements
Site Requirements 2-7