Information Technology Reference
In-Depth Information
12.4.1 Overall Power and Energy Consumption Breakdown
The main contributors to the energy consumption in a data center are the
computing power (also known as IT power), which is the power drawn by
servers to execute a certain workload, and the cooling power needed to keep
the servers within a certain temperature range that ensures safe operation.
Together, both factors account for more than 85% of the total power con-
sumption of the data center, with the other 15% the power consumption due
to lightning, generators, UPS (uninterruptible power supply) systems, and
PDUs (power distribution units) [6].
PPP
=+ +
P
DC
IT
cooling
others
The IT power is dominated by the power consumption of the enterprise
servers in the data center. The power consumption of an enterprise server
can be further divided into three different contributors: (1) the dynamic or
active power, (2) the static or leakage power, and (3) the cooling power due
to the server fans:
P
=
P
+
P
+
P
server
static
dynamic
fan
Dynamic power is the power due to the switching of the transistors in elec-
tronic devices; that is, it is the power used to perform calculations. Leakage
power is the unwanted result of subthreshold current in the transistors and
does not contribute to the microcontroller function. Fan power is becoming
a more important contributor by the day to overall server power [19].
Cooling power is one of the major contributors to the overall data center
power budget, consuming over 30% of the overall electricity bill in typical
data centers [20].
12.4.2 Computing (IT) Power Modeling
12.4.2.1 Static Power Consumption: Leakage Power Modeling
Dynamic consumption has historically dominated the power budget. But,
when the integration technology scales below the 100-nm boundary, static
consumption becomes much more significant, being around 30%-50% [21]
of the total power under nominal conditions. This issue is intensified by the
influence of temperature on the leakage current behavior. There are various
leakage sources in devices, such as gate leakage or junction leakage, but at
present, subthreshold leakage is the most important contribution in mod-
ern designs. Therefore, it is important to consider the strong impact of static
power as well as its temperature dependence and the additional effects influ-
encing their performance. The current consumption of an MOS device due to
leakage current is the one shown in the following equation:
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