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Power Supplies
A couple of years ago, Google decided to build its new facility on the banks of the Columbia
River in The Dalles, Oregon. The facility is two football fields in size with two cooling towers
extending four stories into the sky.
But Google didn’t move to this location on the Oregon/Washington border to get closer
to Microsoft. In fact, Microsoft and Yahoo! are following suit and have plans to build their
own massive datacenters upstream in Wenatchee and Quincy, Washington, 130 miles to
the north.
Is there something gloriously beautiful about the area? Actually there is—the flowing
rivers are harnessed to feed the power that these power-hungry datacenters need. It is the
cheapest power in the country. This location underscores the needs of datacenters—they
need lots of power.
Although you may not be able to uproot everything and move your organization next
to a river, you still need to manage the power in your datacenter. That is a key consideration
when designing or redesigning.
Too Much Power
When systems engineers design power supply requirements for enterprise servers, they
approach it the same way a civil engineer designs a tunnel—they build it for the largest
possible traffic that will ever go into it. Even though the vast majority of the traffic in that
tunnel will be commuter vehicles, they still have to make sure it will be large enough to
accommodate semis and tanker trucks.
It’s the same way for servers. It’s common to specify power supply requirements based
on the maximum system configuration and load requirements. But systems engineers don’t
need to hit the gas so hard. They can specify different power requirements for different
configurations. Naturally, this would cost manufacturers more money, so they tend to just
put the biggest power supply needed in all of a line’s models, regardless of how they will
be used.
For instance, consider the servers in Figure 11-8. Both are from the same line—WasteTech’s
Escalenté line. The WasteTech Escalenté 5000SUX, shown on the left, is configured with
enough hardware to only require 60 W of power. The 6000SUX, on the other hand, is fully
maxed out and contains enough hardware to consume 540 W. Both servers use the same
power supply. Although the power supply feeds the 6000SUX model with enough power,
it provides more than enough power for the smaller server. So much so that it wastes energy.
But the issue isn’t limited to servers in the same line. Many times manufacturers select
a power supply that can fit all of their equipment. Again, cost is the issue. It’s cheaper for the
manufacturer to use the same supply in all their equipment—you’re the one who ultimately
pays for power inefficiency. Further, the planet pays a price, because of the carbon emissions
spent to inefficiently power that device.
Thankfully, many companies such as Dell offer different power supply configurations
so that the customer can choose the right size for the job a particular server is going to do.
This can lower power consumption significantly, especially when factored over the life of
the server.