A study released this summer by Stanford University professor Jonathan Koomey pegs growth in energy use among U.S. data centers at 36 percent from 2005 to 2010 - which is slower than some had predicted but nonetheless significant.
In a down economy where every dollar saved is precious, it's worthwhile to take a look at how to increase energy efficiency in data centers, especially since in many cases significant energy efficiencies can be had without major overhauls to IT equipment or facilities.
1. Determine Your Usage
The first step to becoming more energy efficient is to find out precisely how much electricity your data center is using overall, and where specifically that electricity is consumed. "My first recommendation to CIOs: conduct an assessment of your data center to quantify what your energy use is," says John Tucillo, president and chairman of the board at The Green Grid, a non-profit consortium dedicated to promoting resource efficiency in the data center.
The Green Grid's power usage effectiveness (PUE) metric essentially involves dividing the total power used in a facility by the power used by IT equipment. "You don't need to be sophisticated to quantify basic energy consumption," Tucillo says, "and understanding the PUE in your data center can provide some perspective on how you can be more efficient."
2. Check Out Your Bill
Another fairly straightforward place to launch energy efficiency improvements is by looking at the data center's utility bill a basic practice all too often not done by the IT department. Tucillo recommends CIOs work together with CFOs to examine utility bills in an effort to uncover those areas that could potentially be made more energy efficient. While monthly costs do not always correspond to inefficiencies, they can at least highlight in plain financial terms where opportunities for improvement may exist.
3. Adjust for Virtualization
Once initial assessments are done, CIOs can then examine where to trim electricity usage. While specific strategies will vary, server virtualization is a common strategy and one that can reduce energy consumption and costs significantly by replacing many under-utilized physical servers with a single box. Yet to realize maximum savings from virtualization, or any tactic aimed at efficiency, you've got to consider the ripple effect on the overall data center operations.
"If you have taken your average server and storage device from under 20 percent utilized to somewhere around 70 to 80%, you also should ensure that you've matched your power requirements to that utilization," Tucillo explains. When deploying virtualization, the workload density of certain servers increases, so power and cooling need to be adjusted accordingly for the racks housing those servers as well as for the racks from which servers may have been removed.
A review of the cooling architecture can often lead to significant savings for minimal effort. "I've seen all kinds of ranges for energy efficiency improvement," Tucillo says, "spanning from 40 percent to 20 percent. This can be as straightforward as moving air conditioners closer to those rows of virtualized servers, a strategy called close-coupled cooling. The idea behind close-coupled cooling is to have more control over the delivery of cool air and the capture of hot air. "You want to employ the right cooling required for a particular rack at the time it is needed," Tucillo explains.
4. Fill Empty Spaces
Another issue with virtualization: when servers are removed from a rack, the bypass airflow from the remaining servers typically will increase, creating issues with cooling and energy efficiency, says Don Beaty, president of DLB Associates, an Eatontown, N.J.-based data center design and building firm. Fill the empty spaces within racks, cabling openings, and so forth with blanking panels or curtains.
5. Adopt a Zone Approach
As virtualization adoption increases, one trend gaining in popularity is using zones throughout the data center. Virtualization facilitates the creation of zones as entire racks of servers are removed in favor of fewer, higher density racks. "You can have a highly utilized zone within the data center which in all likelihood is going to enable you to literally shut down whole other areas of your data center," Tucillo explains. In turn, the appropriate power and cooling capabilities can be located precisely where they are needed.
Creating zones organized according to applications can also better enable a data center to balance load, server efficiency and redundancy requirements. For example, back-office applications may live in one zone of the facility while mission-critical systems are in another zone. Rather than deliver the same amount of redundant power and cooling throughout, the mission-critical zone can be targeted for higher levels of redundancy and more robust cooling.
"The opportunity to save energy requires data centers to look at more variables rather than less," Beaty says. "Matching up load, efficiency and redundancy so that they work together is a way to optimize energy consumption."
6. Economize with Outside Air
And don't overlook the outside environment. Beaty says that data centers are often kept too cool; by increasing the temperature in accordance with recent guidelines from ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers), data centers can take advantage of the economizer mode feature that many data center cooling systems now have, which essentially involve using outside air for cooling.
Raising the internal temperature from 70 degrees to 80 degrees, for example, won't compromise IT equipment performance, Beaty says, and will allow a data center to take advantage of many more days each year in which the outside air is cooler than the inside air. The savings derived from using economizer mode can add up quickly. "You can see an energy savings of 50% or more every hour you use an economizer," Beaty says.
Optimizing energy usage throughout a data center can be a sophisticated exercise, but following these few relatively simple steps can potentially deliver big savings to CIOs.
Megan Santosus is a writer and editor in Natick, Mass.
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