How green is your data centre?

Is your data centre an energy hog? If you don’t care now, you will soon.

Ken Brill, founder and executive director of The Uptime Institute Inc., sees the beginnings of a potential crisis. “The benefits of [Moore’s Law] are eroding as the costs of data centres rise dramatically,” he says. Increasing demand for power is the culprit, driven by both higher power densities and strong growth in the number of servers in use.

Server performance is improving faster than energy efficiency is advancing. “If we’re going to get energy efficiency rising faster than the rate of performance increase, we’re going to have to do something radically different than what we’re doing today,” Brill says.

Fortunately, there are many steps that can be taken to start reducing power consumption in existing data centres without making a huge investment or sacrificing performance or availability.

1 Consolidate, consolidate, consolidate. Consolidating servers is a good place to start. In many data centres, “between 10 percent and 30 percent of servers are dead and could be turned off,” Brill says.

Removing one physical server from service saves $560 annually in electricity costs, assuming a cost of 8 cents per kilowatt-hour, says Bogomio Balkansky, director of product marketing for Virtual Infrastructure 3 at VMware Inc. in Palo Alto, Calif.

Once idle servers have been removed, data centre managers should consider moving as many server-based applications as feasible into virtual machines. That allows IT to substantially reduce the number of physical servers required while increasing the utilization levels of remaining servers.

Most physical servers today run at about 10 percent to 15 percent utilization. Since an idle server can consume as much as 30 percent of the energy it uses at peak, you get more bang for your energy buck by increasing utilization levels, says Balkansky.

2 Turn on power management. Although power management tools are available, administrators don’t always use them. “In a typical data centre, the electricity usage hardly varies at all, but the IT load varies by a factor of three or more. That tells you that we’re not properly implementing power management,” says Amory Lovins, chairman and chief scientist at Rocky Mountain Institute in Snowmass, Colo. Just taking full advantage of power management features and turning off unused servers can cut data centre energy requirements by about 20 percent, he adds.

That’s not happening in many data centres today because administrators focus almost exclusively on uptime and performance and aren’t comfortable with available power management tools, says Christian Belady, distinguished technologist at Hewlett-Packard Co. But turning on power management can actually increase reliability and uptime by reducing stresses on data centre power and cooling systems, he says.

Vendors could also do more to facilitate the use of power management capabilities, says AMD’s Brent Kerby. “Power management technology is not leveraged as much as it should be. In Microsoft Windows, support is inherent, but you have to adjust the power scheme to take advantage of it.” Instead, he says, that should be turned on by default.

But power management can cause more problems than it cures, warns Jason William, chief technology officer at DigiTar, a messaging logistics service provider in Boise. He runs Linux on Sun T2000 servers with UltraSparc multicore processors. “We use a lot of Linux, and [power management] can cause some very screwy behaviors in the operating system,” he says.

3 Upgrade to energy-efficient servers. The first generation of multicore chip designs resulted in a marked decrease in overall power consumption. “Intel’s Xeon 5100 delivered twice the performance with 40 percent less power,” says Lori Wigle, director of server technology and initiatives marketing at Intel Corp. Moving to servers based on these designs should increase energy efficiency. (Future gains, however, are likely to be more limited. Sun, Intel and AMD all say they expect power consumption to remain flat in the near term.)

4 Use high-efficiency power supplies. Power supplies are a prime example of the lack of focus on total cost of ownership in the server market. Inefficient units that ship with many servers today waste more energy than any other component in the data centre.Inefficient power supplies can waste nearly half of the power before it gets to the IT equipment. And every watt of energy wasted by the power supply requires another watt of cooling system power just to remove the resulting waste heat from the data centre.

To make matters worse, server manufacturers have traditionally overspecified power needs, opting for a 600-watt power supply for a server that really should only need 300 watts, says Rich Hetherington, chief architect and distinguished engineer at Sun.

Power supplies are available today that attain 80 percent or higher efficiency even at 20 percent load, but they cost more. Moving to these more energy-efficient power supplies reduces both operating costs and capital costs, however. “If they spent $20 on [an energy- efficient] power supply, you would save $100 on the capital cost of cooling and infrastructure equipment,” Lovins says. Any power supply that doesn’t deliver 80 percent efficiency across a range of low load levels should be considered unacceptable, he says.

5 Break down internal barriers. Although IT has carefully tracked performance and uptime, most IT organizations aren’t held accountable for energy efficiency because the IT function is stovepiped from the facilities group. IT generates the load, but facilities gets the power bill, says Brill. Breaking down those barriers is critical to understanding the challenge and providing a financial incentive for change.

The stovepiping problem has also afflicted IT equipment vendors, says Lovins. Engineers are now specialized, often designing components in a vacuum without looking at the overall system or data centre in which their components will play a role.

6 Follow the standards. Several initiatives are under way that may help users identify and buy the most energy-efficient IT equipment. A certification program called 80 Plus, which was initiated by electric utilities, lists power supplies that consistently attain an 80 percent efficiency rating at load levels of 20 percent, 50 percent and 100 percent.

Under a U.S. congressional mandate, the Environmental Protection Agency is working with Lawrence Berkeley National Laboratory to study ways to promote the use of energy-efficient servers. An Energy Star specification could be in place later this year.

The nonprofit Standard Performance Evaluation Corp. is also working on a performance-per-watt benchmark for servers that should help provide a baseline for energy-efficiency comparisons. The specification is slated for release this year.

7 Advocate for change. IT equipment manufacturers won’t design for energy efficiency unless users demand it. Robert Yale, principal of technical operations at The Vanguard Group Inc. in Valley Forge, Pa., says his company is involved with The Green Grid and other industry organizations to push for greater energy efficiency.

Joseph Hedgecock, senior vice president and head of platform and data centres at Lehman Brothers Inc., says his company has been lobbying vendors for more efficient server designs. “We’re trying to push for more efficient power supplies and ultimately systems themselves,” he says. 079669

Robert L. Mitchell is a writer with over 20 years experience in IT.

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