The design and operation of Internet data centers the art of compromise. One way to simplify the choices is to group the requirements in to different levels.
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Level I |
Level II |
Level III |
Level IV |
Level V |
|
|
Grade C |
Grade B |
Grade A |
Grade AA |
Grade AAA |
|
Examples |
Single site data
processing facility, limited off-site impact due to failure |
Corporate data processing
center, end-office telecommunications office, local impact due to failure |
Toll-office
telecommunication facility, Internet collocation center, regional impact due
to failure |
International financial or
airline communication facility, national impact due to failure |
Critical military
communications center, One-of-a-kind control center, international impact due
to failure |
|
Size (substitute
measurement for "importance") |
Less than 2,500 square
feet |
2,500 to 80,000 square
feet |
80,000 to 150,000 square
feet |
more than 150,000 square
feet |
Specialized requirements |
|
General design |
Meets minimum local
building code requirements. System is able to withstand the temporary loss of
off-site commercial utility power. |
Meets code enhanced
requirements such as NEBS, Factory Mutual, UL, etc. System is able to
withstand a failure of a single active component with minimal impact to
critical loads. |
Meets requirements for
essential facilities. System is able to withstand a failure of a single
active component. Planned maintenance without impacting any critical load.
Maintenance may affect fault tolerance. |
Systems are able withstand
a single, worst-case infrastructure failure without impacting any critical
load. Planned maintenance activity
without impacting any critical load or fault tolerance. |
Design for maximum
probable event. Systems are designed to supply services continually during
any scheduled or unscheduled, natural or man-made disruption. |
|
Program elements |
The design shall eliminate
or reduce the probability of events that can cause injury or death to
personnel or damage to or loss of equipment or property. Systems of high
complexity or peculiarity shall be identified and minimized. |
Standardized design to
minimize use of custom or unusual components. Individual system and subsystem
test and checkout requirements shall be developed to ensure safe and normal
operation of the system. |
Reliability, availability
and maintainability requirements shall be implemented during design to
maximize the availability of the systems. |
Consolidated systems test
program covering all phases of testing to develop confidence in the systems
and provide for interim and final acceptance of equipment and complete
systems. |
Human factors engineering
will ensure that reliability, availability and safety are not degraded
through human activities during operation or maintenance. The design incorporates, within program
constraints, the highest level of inherent safety. |
|
Reliability, availability
and survivability (design) |
99.8% |
99.9% |
99.99% |
99.999% |
99.9999% |
|
Estimate of real-world
availability annualized over facility lifetime |
99.7% -26 hours |
99.85% -13 hours |
99.97% -2.6 hours |
99.998% -10.5 minutes |
99.999% -5.25 minutes |
|
Probable design threat
considerations |
Loss of
commercial power |
Component failure, accidental fire |
Severe weather (blizzard,
thunderstorm, high winds, flooding), intrusion, simple human error |
Natural hazards
(earthquake, hurricane, volcanic eruption, wildfires), individual attacker,
civil unrest, nearby explosion |
Regional disaster
(industrial or nuclear accident), war, trained attackers, bombing, stand-off
weapons |
|
Life-cycle cost analysis |
Initial cost is the
primary factor |
5 to 15 year occupancy |
10-30 year occupancy |
20-50 year occupancy |
Permanent occupancy, 25
years or longer. |