How to Achieve 40 Percent Energy Savings in Your Data Center (
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Today's data center managers have many techniques to reduce their data center's energy consumption, but a mixture of techniques is often required to achieve energy saving targets. The key to judging success of any energy reduction strategy is the ability to accurately measure results along each step of the way. Here, Knowledge Center contributor Joe Polastre illustrates how power management technology can be used to achieve up to 40 percent energy savings in your data center.
Everyone's
talking about how the 35 to 40 percent energy savings promised by
so-called green data center initiatives can help MIS operations
dramatically reduce both their operating expenses and their
environmental impact. But despite the buzz, there is not much being
said about the most efficient and cost-effective way to achieve these
savingsor how to measure them. Meanwhile, the ambitious claims being
made by many hardware and software vendors make it hard to understand
how much their particular solution adds to your operation's overall
energy efficiency.
Instead of focusing on the exotic
technologies used by newly constructed, ultra-efficient data centers
such as those used by Google, this article will deal primarily with the
best ways to improve the efficiency of the many middle-aged and older
facilities that still constitute the majority in use by enterprises,
universities and government agencies. Since most real-world facilities
have finite budgets and cannot afford downtime, we'll pay special
attention to upgrades that offer fast payback periods and pose a
minimum of disruption to normal operations.
Metrics, models and methodologies
One popular efficiency ratio that
we'll use to understand the effectiveness of our upgrades is the Power
Usage Effectiveness (PUE) factor, defined as the ratio between the
power consumed by the data center facility itself and the power
consumed by its IT equipment.
PUE = Total Facility Power/IT Equipment Power
Although PUE is a widely-accepted
way to describe how data centers use their energy, care must be used
when interpreting the results it produces. One must always keep in mind
that PUE is most useful for tracking the effect of changes you make on the infrastructure side and less useful
for tracking the improvements resulting from reducing the energy
consumption of your data center's IT equipment. Because it is a
non-scalar ratio, cutting your equipment power consumption can actually
result in a higher PUE.
The data center we'll use in this
example is a traditional "MIS center" that supports the computing and
networking needs of a mid-sized, brick-and-mortar enterpriseperhaps an
insurance company, manufacturer or biotech operation. Its
7,500-square-foot floor plan was carved out of an underused floor of
the company's headquarters back in the late 1980s. This
was a time when equipment was expensive, energy was cheap and the room
still bears the white walls, white floors and bright lighting that were
the standard decor of the era. The mainframes and mini-computers it
once housed have given way to a patchwork of servers and disk farms
that have been added over the years as demand dictated and space
permitted.
Our model data center's power
consumption has steadily grown with the addition of new equipment and
now stands at around 1.5MW. Although the average PUE for all data
centers is somewhere around 2.7, most of the "mature" facilities we're
concerned with have PUEs that range from 3.0 to 5.0, so it's reasonable
to assume that ours runs in the neighborhood of 4.0.
IT Infrastructure 
