The use of colocation data centers by business and
industry to store, manage, and exchange data has
grown tremendously over the past decade and is likely
to continue due to the convenience and economic
advantages such facilities provide. The issues to consider
when selecting a colocation data center depend upon
many factors ranging from the type and criticality of
data, to geographical and reliability considerations.
RELIABILITY
All colocation data centers have three things in common.
They all provide space, power, and environmental
conditioning. What sets them apart, among other
things, is reliability. According to Gross and Schuerger,
(2006), The term “reliability” is generally defined as the
probability that a product or service will operate properly
for a specified period of time under design operating
conditions without failure. The reliability of a colocation
data center power system can be affected by multiple
factors. Curtis, 2011, notes that greater than 50% of data
center downtime can be traced to human error related to
the design, construction, commissioning, documentation,
training, or maintenance of the facility.
Reliability requirements are not uniform. For example,
colocation data center serving an online meeting service
would not necessitate the same level of reliability as that
required for a 24/7 banking institution. A relatively low
level of reliability or uptime might suffice for the former,
perhaps 99.99%, whereas a much higher level would be
required for the latter, perhaps 99.9999%.
The quality and reliability of utility power varies
dramatically depending upon region and location. Aside
from hurricanes, tornadoes, ice storms, lightning, and
earthquakes, most major urban utilities are relatively
reliable at around 99.9%, or equivalently, 8.76 hours of
downtime per year per the IEEE Gold Book, 1997. Still,
researching the reliability of the utility serving the data
center location and the data center’s relationship with
the utility is recommended as an initial step in evaluating
a colocation data center.
TYPES OF COLOCATION DATA CENTERS AND
ASSOCIATED POWER REQUIREMENTS
Colocation data center power systems will typically
consist of a utility service, power distribution system,
emergency generator, automatic transfer switch, and
an uninterruptable power source. Redundancies or
multiple redundancies in each of these systems results in
a more reliable system overall. However, when selecting a
colocation data center, usually the design, construction,
commissioning, and documentation are completed
leaving ongoing training and facility maintenance
as the only avenue to affect reliability. A review of
commissioning documents, training requirements, and
maintenance schedules and documentation is essential in
evaluating facility reliability.
According to Psychz.Net, 2015, colocation data centers
typically provide several levels of service depending upon
the facility.
Cabinets
Services range from a 1U server location in a shared rack
with other customers to a private 42U lockable server rack
cabinet sharing raised floor space with other tenants.
Cages
The next level of service is a secure cage with wire-mesh
walls within the common raised floor area containing
several server racks.
Suites
At the higher end of the of the cost scale is the secure
suite. A suite is typically a fully enclosed space with a
raised floor, solid walls, and a lockable door. A suite may
share power and environmental conditioning with other
tenants or have separate dedicated systems.
Modules
Colocation data centers with sufficient available space
may offer data center modules at a premium cost.
Modules are essentially compact, secure, self-contained,
data centers within the data center and contain their own
cooling and power infrastructure.
COLOCATION DATA CENTER POWER CONSIDERATIONS
Some considerations for the colocation data center
include an evaluation of the normal power source,
emergency power source, and reliability. There is no one
best solution for all applications, but an evaluation of
each of these factors is critical to a tailored solution.
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