Trends in data center power usage

Data center power usage is on the rise, but consumption is not as high as some predicted. In this Q&A, an expert explains what is behind the data.

Back in 2007, the United States Environmental Protection Agency predicted that worldwide energy use for servers and data centers would double from 2005 to 2010, but an independent report by Jonathan Koomey, a consulting professor in the civil and environmental engineering department at Stanford University, issued in 2011, said the actual increase was only about 56%. In the United States, the increase was even smaller, coming in at 36% over that five-year period. Still, data center power consumption is on the rise, so the conversation about energy use and the cost of powering our data centers is more important than ever.

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Trends in data center power usage

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In this podcast, Nick Martin, assistant site editor for, interviewed Julius Neudorfer, chief technology officer and founder of North American Access Technologies Inc., about why data center power consumption isn’t growing as fast as some experts expected and uncover what this means for data center professionals. 

Nick Martin: What do you make of this report? Is the lower power consumption number because of emerging technologies, such as server virtualization and more power-efficient servers, or do you see other factors involved?

Julius Neudorfer: That’s a good question. Clearly, virtualization is taking hold and is impacting the utilization numbers, so we’re getting more compute rates for each box. Of course, that isn’t happening in every data center, but it accounts for a substantial portion of what’s happening. We are getting more computing power from CPUs, and Energy Star servers are beginning to creep into inventory, so new data centers coming online are more efficient. From the infrastructure point of view, data center power usage effectiveness (PUE) is improving. More energy is going into the IT load and less is being lost to power and cooling.

Overall, when you look at these numbers, this report is quite thorough. It was based primarily on statistics on server shipments over that period of time–as was the original [EPA] report. The report’s author, Jonathan Koomey, has done a lot of research and found a lot of industry information to put into the report. But, the projections are primarily based on statistics about server shipments. Take a step back from the industry perspective and consider that the report shows only a 36% increase in data center power consumption. That is a bit different from my perspective on the industry, with the real buildup of mega data centers and the building of bigger data centers with greater power capacity. So, I’m not sure everything has been taken into account in the report.

Based on the statistics used, the actual power used may be somewhat higher than the report indicates. I don't have any hard data, because I didn't perform my own analysis, but I would've liked to have seen something along the lines of a survey of the total number of data centers and the average watts per square foot. Or, perhaps a look at other related information, such as the uninterruptable power supply shipments at that time and what the total capacity was, instead of just server shipments. Or, maybe look at shipments of backup generators, or perhaps even a survey of utility power used by data centers of a certain size. This information might have shown that the power that is actually being used by the data center industry is somewhat higher than the report indicates. Again, this is just supposition, but I would've liked to have seen that as a counterpoint. In that sense, I'm hoping that the report is right. We'd always like to see less energy usage, but I still have to wonder whether the usage is actually higher than the report indicates.

Martin: How much has the recession, versus power-saving technologies, affected power consumption in data centers, and can we expect to see a spike in data center power consumption when the economic environment picks up?

Neudorfer: I think that the recession definitely had an impact on both capital spending and the number of servers shipped, which was part of the report’s conclusion. Capital money for server placement was limited, and people were hanging onto their servers longer. That is going to have the effect of pent up demand once we come out of the recession. It will certainly drive data center power usage up as more servers are purchased. We see a lot of people moving into colocations because of capital restrictions. Now, colocations are starting to fill up and have rising densities. As the economy spins up, I think data center power consumption will increase. The question is, to what point? I don't have an economic crystal ball here.

Martin: What energy-saving steps can IT professionals take right that will have the best return on investment?

Neudorfer: Clearly, one of the things that servers do is stay on 24 hours a day. That brings in the 8,760 rule. That number, 8,760, is the number of hours in the year. Essentially, if you plug in a server, it consumes power consistently over a 24-hour period, or 8,760 hours in a year. If you start calculating some usage numbers, such as 11½ cents per kilowatt-hour, that equates to about $1,000 per kilowatt year for every piece of IT load you have in the data center. With a PUE of two, that winds up costing about $2,000 a year. Average server life is about three years, so that equates to about $6,000 for every kilowatt of IT used over the server’s life. The problem with servers, especially in a capital-restricted environment, is that people do not tend to replace them as often as they'd like. Therefore, they may have some older servers that aren’t as efficient as new models. So, you can spend $6,000 for every kilowatt for a server that was purchased years ago, and yet if you replace it today, you could probably cut that number in half, because a new server will be so much more efficient. But it's difficult to make that argument when your company is looking to cut back across the board.

Last year, the Energy Star program put together a profile for servers that radically alters the power efficiency rating that a commodity 1U server must meet to qualify for an Energy Star rating. Typically, 1U servers could use about 100 to 200 W, even while idle. The new Energy Star profile for 1U servers that include one CPU, hard disk and power supply, is now 55 W. So you can see, when you spend $6,000 per kilowatt-hour over a year, cutting the IT load by 50% on a typical server, you can save a tremendous amount of cost and operating capital. If your servers are two years old or older, push real hard to try to get replacements early. Of course, as the company's capital is constrained, you can look to leasing servers.

The other options to reduce data center power usage are in infrastructure. Basically, you can raise the temperature in your data center safely. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has made a point of that. Many people are still using the old formula of keeping data centers at 64 degrees Fahrenheit. They're wasting a lot of energy. Even if you’re comfortable bumping it up to 75 degrees Fahrenheit, you can knock down your cooling costs by about 10%.

Martin: How about power savings over the intermediate term? What are some strategies or technology deployments IT pros should consider to further reduce data center power consumption over of the next several years?

Neudorfer: In the era of storage, data deduplication is important and almost vital. The amount of information we are storing is rising far beyond typical compute requirements. We are now storing more data than we ever thought we would need. Storage technology is advancing by leaps and bounds. A lot of people are now moving towards solid-state storage. With solid-state storage, cooling parameters will change. You can use far less energy to cool a solid-state drive when compared to spinning disk storage. Energy Star is also now being applied to storage. They have a program now for Energy Star certification in storage arrays. So these are things that are certainly going to help to reduce data center power as we move toward an environment where we store everything. The other thing I mentioned is the ability to raise temperatures in the data center, which was historically limited by storage. Even ASHRAE is now beginning to raise those windows up to 95 or 100 degrees Fahrenheit for the newer type of equipment, which allows us to have more free cooling by using ambient air. So these steps, such as raising the temperature in data centers, can all be taken safely in a short period of time or within the next few years.

Martin: What can we expect in terms of data center power consumption trends in the next five to 10 years? Do you expect continued modest growth or other trends emerging?

Neudorfer: We are beginning to see more and more things move toward the data center. Is the cloud really pulling in things that were never there before? If you look at organizations, such as Netflix Inc., their video streaming is expanding exponentially. That takes a huge amount of storage and processors.

Others are doing the same thing. Inc. just announced its Kindle Fire. The interesting thing is, while other tablets are pushing 16 or 32 GB of storage, Amazon went the other way. Their Kindle Fire only has 8 GB, which you would think would be an inhibitor. But what Amazon did to counter that is it offered people who purchased the Kindle Fire free storage on the Amazon cloud. They've taken the storage off the device and moved it back to a centralized processing model where the storage exists in the data center.

Smartphones cannot continue to have endless storage, and more people are beginning to use cloud-based services to store their data. So for the next five to 10 years, we're going to see huge increases in storage and huge increases in bandwidth to get there from mobile applications. Streaming video is driving this beyond any previous expectations for bandwidth or storage. For equipment makers to keep filling the pipeline, they're going to have to mitigate their energy use more than they are. They will have to be more productive, because energy is going to be more expensive, and the IT side is going to have to fine-tune their equipment. The infrastructure side is really going to focus on keeping its PUE numbers down in the coming years.

I think we’re going to hit an inflection point in the next five years or so, where we come to an equilibrium between the need for more compute and storage and the efficiencies of the storage and compute process. Like anything else, these are just projections, but the need to constrain energy across the board is worldwide. PUE has been adopted worldwide. I think you'll see a peak and plateau in energy uses soon, but compute power and storage power will continue to rise. That's where I think we’re going, but of course, someone has to polish the crystal ball every now and then.

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