Ambient Relative Humidity Recommendations; Facility Power Requirements - Sun Microsystems Sun Fire E6900 Site Planning Manual

3.1.2

Ambient Relative Humidity Recommendations

The ambient relative humidity levels between 45% and 50% are the most suitable for
safe data processing operations. Under certain circumstances, most data processing
equipment can operate within a fairly wide environmental range (20% to 80%), but
the optimal goal should be between 45% to 50% for several reasons:
The optimal range helps protect computer systems from corrosivity problems
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associated with high humidity levels.
It provides the greatest operating time buffer in the event of environmental
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control system failure.
This range helps avoid failures or temporary malfunctions caused by intermittent
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interference from static discharges that occur when relative humidity is too low.
Electrostatic discharge (ESD) is easily generated and less easily dissipated in areas
where the relative humidity is below 35%, and becomes critical when levels drop
below 30%. The 5% relative humidity range may seem unreasonably tight when
compared to the guidelines used in typical office environments or other loosely
controlled areas, but it is not so difficult to maintain in a data center because of the
high efficiency vapor barrier and low rate of air changes normally present.
3.2

Facility Power Requirements

To prevent catastrophic failures, the design of your power system must ensure that
adequate power is provided to your Sun Fire system. Use dedicated AC breaker
panels for all power circuits that supply power to your system. Electrical work and
installations must comply with applicable local, state, or national electrical codes.
Provide a stable power source, such as an uninterruptible power system (UPS), to
reduce the possibility of component failures. If the computer equipment is subjected
to repeated power interruptions and fluctuations, it is susceptible to a higher
component failure rate than it would be with a stable power source. Every Sun Fire
system requires its own customer-supplied circuit breaker and AC receptacle for
each power cord.
Each power cord will also supply your system with proper earth ground. Sun has
tested both Sun Fire E6900 cabinets and Sun Fire cabinets for radiated and
conducted emissions and have determined there is no difference in emissions with
or without a ground strap grounding the cabinets. No additional earth grounding is
necessary but, it may be added if desired.
The Sun Fire E6900 system has dual Redundant Transfer Units (RTUs) with four
Redundant Transfer Switches (RTSs). Two totally independent AC power sources are
needed for input power redundancy. The AC power sources must be derived from
independent power company utility feeds and Sun recommends that each be backed
Chapter 3 Environmental and Electrical Specifications 3-3