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Crunching the numbers on data-centre efficiency

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• Measure,
• Output,
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• Consumption

Sally Whittle ZDNet.co.uk

Published: 20 Nov 2007 11:42 GMT

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From carbon-neutral search engines to energy-efficient power supplies, we're surrounded by products that promise to increase energy efficiency and reduce our carbon footprint. But, while there are a lot of marketing budgets being thrown at the issue, there appears to be little real enthusiasm for sustainability in IT departments.

"The problem is that most IT managers simply aren't that interested in being green," said Mick Walker, an energy consultant with IBM Global Services. "Certainly, it's not something that many customers ask us about today."

However, Walker argued that this is something that's going to change over the next few years, as IT departments are forced to face up to the true cost of running their data centres. "Energy efficiency won't be driven by environmental issues; realistically, it's going to be because the finance director wants to cut the electricity bills," he said.

According to one recent US survey, data centres account for 1.5 percent of all the power consumed in that county. The cost of powering data centres is estimated to be $4.6bn (£2.2bn) each year, and power requirements are predicted to double within the next four years. Assuming power prices remain steady, that means we could be spending almost $10bn a year powering data centres by 2011.

The cost of electricity is only one factor that will put energy efficiency on the agenda, observed Graham Titterington, a principal analyst with Ovum. "Companies are simply going to hit a point when this is a crisis; when the next server will cost millions because they need to build a new data centre, to get more power or to get more space," he said.

The good news is that experts reckon that being more energy efficient could drive down power consumption in the data centre to 2001 levels — saving around 15 percent on current energy costs.

The bad news is that measuring your company's green credentials is far from straightforward. "The obvious answer is just to look at the electricity bills. They'll tell you how much power you're using, and how much it costs," said Walker. "However, that's a very blunt instrument and won't tell you an awful lot."

Instead, you could use standard calculations to translate your energy consumption into a carbon-output figure, using, for example, the calculators developed by the Energy Saving Trust and The CarbonNeutral Company. The problem is that coming up with a carbon-output figure isn't particularly useful, according to Ted Shann, a sustainability manager with BT. "Knowing how much energy you use or how much carbon you produce isn't very useful in practical terms," he said. "Apart from changing your energy supplier, what do you do?"

The first step when it comes to measuring your environmental credentials is knowing exactly what to measure. This means analysing the data centre to understand exactly what energy is consumed, and where. Unless you know what elements of the data centre are using power, it's impossible to improve energy efficiency, Walker said. "Remember: you can only control what you can measure, so you need a good understanding of how much power each service uses to start with."

The first item on the list is the IT infrastructure itself, which is likely to account for around 45 percent of the energy bill, said Walker. To help customers get a clear idea of the power consumption of servers, IBM has introduced what it calls "active power management" in several of its ranges. For example, the blade servers have an in-built Active Energy Manager which gives real-time information about energy usage. The System z features IBM's "gas gauge", which performs a similar function.

This type of feature, which is also available on HP servers, is important because IT managers are otherwise relying on the maximum power-consumption figures for...

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