2003 American Power Conversion. All rights reserved. No part of this publication may be used, reproduced, photocopied, transmitted, or
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5
Availability Imperatives
Imperative
Underlying problems
Solution Requirements
Proper cooling airflow to IT
equipment
IT equipment compaction and rising heat
densities are causing equipment to fail
prematurely.
Servers are getting deeper and thinner
which allows more servers to be installed
in a rack and therefore more heat and
cables.
Customers don't know if the rack they are
using is providing proper airflow for their
equipment.
The temperature up and down the front of a
particular rack can vary 10
°C (18°F). This
effect is unexpected and the reasons why
this happens are unclear to the users. This
places unexpected stress on individual
pieces of IT equipment and results in
premature failure of equipment above the
temperature gradient.
Well-designed perforated doors should
have over 830 in
2
(0.53548 m
2
) of
ventilation area that can provide sufficient
"unassisted" airflow to ventilate IT
equipment in a 42U rack.
Cable management should prevent power
and data cables from obstructing exhaust
airflow.
Vendors that validate the cooling
effectiveness of their rack designs using
CFD (Computational Fluid Dynamics) and
environmental chambers.
Tightly sealed rack enclosures and
accessories that prevent hot exhaust air
from returning to areas on the front of the
rack, and assure that cool supply air is
distributed uniformly up and down racks.
Provide dual power sources to
the equipment
IT equipment today is available with single
and redundant power supplies but no
provision is made for bringing power
redundancy to the rack.
Easily configure the rack to provide dual
power paths to single or dual corded IT
equipment.
Physical security
In trying to provide ample air, power and
data requirements, rack enclosures leave
critical equipment vulnerable to sabotage
or human error.
Hinges and fasteners located on the inside
of the doors to prevent access to
equipment.
Doors should have unique combination
locks combined with a master key or
electronic locks integrated with the building
security system.
Side panels should be keyed.
Seismic capability (UBC)
Racks systems, located in Zone 4 regions
of the U.S., that are not designed to be in
compliance with the Universal Building
Code (UBC) for Zone-4 seismic regions
risk catastrophic lose of the IT equipment
they are protecting.
All racks located in a Zone-4 region should
be in compliance with UBC.
Minimize human error
Shallow and constricted racks have a
propensity to exacerbate human error.
Rack based power strips that use small
unreliable circuit breakers can cause load
drops and represent another single point of
failure.
Resetting a circuit breaker inside a critical
rack can lead to further downtime.
Deep racks that allow ample room for
working with less fatigue and visual
obstruction.
Remove circuit breakers from the IT rack.
Use rack based power strips without circuit
breakers for improved reliability.
Circuit breakers should be easily
accessible and located at the panel to
avoid entering the critical IT rack.
