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Luckily, he added, the data centre is still ripe for energy efficiency improvements. “There are a huge number of boxes that are sitting in our data centres doing nothing,” he observed.

That is not to say that managing data centre efficiency is a new phenomenon – it is an established art with standard best practices and metrics. Chief among these metrics is power usage effectiveness (PUE), the default description of how effective a data centre is at converting raw electricity into IT functionality.

But according to Stephen Whatling, divisional director at engineering consultancy HurleyPalmerFlatt, while still useful, PUE is often misused. “PUE has become a weapon in many people’s hands,” he explained. “As a metric, it’s produced some misleading results.”

PUE is calculated by dividing the total amount of power a data centre consumes by that which is used by the IT equipment. A PUE score of around 2 for a data centre would be considered ‘average’, while a PUE of 1.5 is deemed ‘efficient’ and anything below this is difficult to achieve.

Whatling believes that this calculation is too crude, especially if it used to compare the relative efficiency of two or more data centres. A number of external factors can effect the calculation, such as the climate in which the data centre resides, and the time of day that the measurement was taken. As Whatling put it to delegates, “Everyone seems to want a snapshot number, but data centres are in constant flux. You’ve got to dig deep to find out about that number and what’s behind it.”

A more useful measure, Whatling said, would be one that tied energy consumption to the productive output of the IT systems, but this requires a standard definition for IT productivity. “An IT productivity measurement is a long way away,” he informed delegates, “and it could be contentious. PUE is the best metric there currently is.”

The virtual truth

That the cost control and energy efficiency imperatives are today inseparable was further reflected in the discussion around virtualisation at the Future of the Data Centre conference.

Tom Brand, service director at IT infrastructure consultancy GlassHouse Technologies, argued that virtualisation provides a “huge opportunity for carbon footprint reduction” by allowing organisations to ramp up their server utilisation rates, cutting hardware requirements and subsequently energy bills. This “massive consolidation” brings with it “billions of dollars of cost reduction, and virtualisation is the ‘killer app’ for enabling this”, he said.

Nick Miller, EMEA CTO at outsourcing provider ACS ITO, agreed with Brand’s assessment that virtualisation has the potential to reel in power consumption in data centre racks, while also adding his own contribution to the day’s overarching debate. “Some 90% of the energy used to supply these servers is going to waste,” Miller said. “There’s a lot to be had from virtualisation.”

There are, he added, other opportunities for improving the energy efficiency of data centres, including raising the atmospheric temperature, thereby reducing the need to power cooling systems. “Manufacturers are increasing the standard operating temperatures of their equipment. A lot of people are running their data centres far too cold.”

Not everyone saw virtualisation as a panacea to cost and efficiency concerns. Liam Newcombe, CTO at software vendor Romonet, told delegates that while it cannot be disputed that virtualisation improves server utilisation, it has also made it harder to divine the productive contribution of hardware resources. “[Virtualisation] has broken the tie between application and server”.

Without clear visibility into the functional dependencies of their IT infrastructure, organisations can overload their hardware, thereby damaging efficiency. “Many [data centre] operators that have virtualised have seen a growth in energy consumption,” Newcombe warned.

Newcombe echoed Tim Anker’s suggestion that when assessing outsourced data centre offerings, greater consideration must be given to power consumption as it is an ongoing cost. Indeed, he said, a focus on the short-term expenses of data centre deployments has blinded many organisations to the ongoing financial burden. “People have focused on the cost of deployment, but most of the cost is submerged,” he said.

When the extent to which businesses and public sector organisations would have to slash cost as a result of the economic downturn first became clear, there was some concern that the impetus to improve energy efficiency might fall by the wayside. But as the Future of the Data Centre conference proved, cutting cost and improving energy efficiency are not just complementary – they are the very same thing.