How Virtualization Figures into Power Savings

By Chris Preimesberger  |  Posted 2008-12-04 Print this article Print

How does virtualization figure into this power-saving equation? Does it save-or cost us-energy?

When you transfer a vast amount of data on a virtualized basis, you're going to be activating areas within the data center that have probably cooled down and not processed anything in awhile. So the local building or energy management systems may have throttled those areas down to save energy.

But you need to be able to go there because virtualization, to be successful, has two components to an equation that most people don't realize: You virtualize IT, but you also have to have the equal virtualization of the facility.

So, "VxIT," from a mathematical perspective, is equal to "VxFacility." You have to keep the two in harmony. There is a reason for that. When you virtualize a process on the IT side on a data center that is not a green field, the problem is that the data center was designed with upper and lower [power] limits.

We always knew what happens when you exceeded [a power limit]: The system shuts down. But we did not understand what would happen if you could actually drive a process below its design requirements. Power and cooling are designed for a window of operation. When you go below the lower limits of the window, what happens from a cooling perspective? Systems will shut off. Our root cause analysis is done, the data center crashed, yet no one knows why. The system simply shut down.

What happened was, virtualization saw there was a problem [and] it transferred the workload someplace else, so that line went above the design requirement again. Same thing with the power systems. The frequency among multiple UPSes [uninterruptible power supplies] can become unstable. When that instability exceeds the threshold level, they'll take themselves offline.

The safety circuits are operating; they're doing what they were designed to do. So what's the answer? The answer is to understand that when you virtualize the IT, you have to review the facility part.

Chris Preimesberger Chris Preimesberger was named Editor-in-Chief of Features & Analysis at eWEEK in November 2011. Previously he served eWEEK as Senior Writer, covering a range of IT sectors that include data center systems, cloud computing, storage, virtualization, green IT, e-discovery and IT governance. His blog, Storage Station, is considered a go-to information source. Chris won a national Folio Award for magazine writing in November 2011 for a cover story on and CEO-founder Marc Benioff, and he has served as a judge for the SIIA Codie Awards since 2005. In previous IT journalism, Chris was a founding editor of both IT Manager's Journal and and was managing editor of Software Development magazine. His diverse resume also includes: sportswriter for the Los Angeles Daily News, covering NCAA and NBA basketball, television critic for the Palo Alto Times Tribune, and Sports Information Director at Stanford University. He has served as a correspondent for The Associated Press, covering Stanford and NCAA tournament basketball, since 1983. He has covered a number of major events, including the 1984 Democratic National Convention, a Presidential press conference at the White House in 1993, the Emmy Awards (three times), two Rose Bowls, the Fiesta Bowl, several NCAA men's and women's basketball tournaments, a Formula One Grand Prix auto race, a heavyweight boxing championship bout (Ali vs. Spinks, 1978), and the 1985 Super Bowl. A 1975 graduate of Pepperdine University in Malibu, Calif., Chris has won more than a dozen regional and national awards for his work. He and his wife, Rebecca, have four children and reside in Redwood City, Calif.Follow on Twitter: editingwhiz

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