Data centre efficiency has become the holy grail of IT professionals. Virtualisation, together with public and private cloud and rising energy costs have changed the nature of enterprise IT, highlighting new opportunities and challenges.

Vendors have responded with new products that do more than simply put a coat of greenwash over their established product lines.

In February 2012, for example, HP launched its latest range of ProLiant Gen8 servers, claiming they offered a 10% reduction in energy consumption on the previous generation of ProLiant machines thanks simply to increased automation of manual processes.

More radically, HP announced that its ultra-low energy consumption Project Moonshot servers, based on smartphone processors, would be out in the first half of this year. Other vendors are offering equally innovative products and making similar claims of serious efficiency gains on offer.

Claims, of course are one thing, meaningful and agreed measurements are another.

One of the first efforts to agree a standard came from the Green Grid, which developed Power Usage Effectiveness or PUE, a measurement of how much power is used by hardware in a data centre. The figure is the ratio between the power used by infrastructure to the power delivered into the data centre.

The Green Grid is a non-profit organisation made up from a mixture of end users, policy makers, technology vendors and utility companies with the aim of improving efficiency in the data centre. It currently has over 175 members, including industry heavyweights like eBay and has representatives from the likes of Intel, Microsoft and Dell on its board.

Though analyst group Ovum has described PUE as “imperfect,” it also called it a “touchstone,” becoming the industry’s first metric to measure data centre efficiency in an easy to understand way. The analyst firm even claimed PUE ratings have become so important to some companies, that board level executives can have their salaries based on them.

Steve Wallage, managing director of consulting firm Broad Group, is another to highlight the imperfections of PUE, calling it “a very rough measure.”

“First, companies generally self-certify so there is no independent verification,” he said.

“It is being overtaken by marketers who claim even lower PUEs and as the measure can vary widely, depending on issues such as utilisation, time of day, type of usage etc... there is some manipulating of figures.”

But the main problem with PUE is it only measures one thing - the efficiency of infrastructure. A data centre is so much more than that, so to discover its true efficiency, one must look at the entire environment, rather than just one element.

“PUE may be the current gold standard, but PUE alone is not an adequate strategy for data centre efficiency,” added Ovum.

Other metrics for measuring data centre efficiency have emerged but Wallage warned they were often been extremely specific, such as ASHRAE for cooling, BICSI for cabling or TIA-942 for telecoms.

A recent report, The business case for data centre metrics, by Ovum analyst Rhonda Ascierto - the analyst who questioned the effectiveness of PUE – notes that the Green Grid itself has designed a number of other metrics it wants to become industry standards.

The aim is not to measure for the sake of measurement, but to make it easier for businesses across the globe to track their operations, their environmental impact and compare the performance of different technology on one common measurement.

“When combined, The Green Grid metrics and PUE will help organisations not only reduce costs and increase efficiency, but also create opportunity for revenue and business growth,” the report suggested.

The Green Grid believes it is up to an organisation’s chief information officer (CIO) to decide who should take charge of data centre efficiency.

“Data centres are the factories of our 21st century information-based economy, so the person most responsible for both capital and operating expenses to keep that “factory” operating at peak efficiency is typically the CIO,” said Roger Tipley, board member and vice president at The Green Grid.

So what tools are on offer to the IT leader?

There are two main metrics in addition to PUE brought to the table by The Green Grid which have won the support of Ovum, Wallage and other industry analyst and vendors - Water Usage Efficiency (WUE) and Carbon Usage Efficiency (CUE).

WUE addresses an issue The Green Grid claims “is emerging as extremely important in the design, location and operation of data centres in the future.”

The main function of water in a data centre is to cool down the heat-emitting hardware stacked up around the room. As such, vast amounts are used but up until now, have not been taken into account when measuring efficiency of the environment.

“Total usage is important because focusing only on reducing site usage may lead to unintended averse trade-offs, for example reducing on-site water use may increase electricity consumption and thereby increase water use at the power-generation source,” claimed Ovum.

WUE is split into two types. The first is site WUE, which measures how much water has been purchased from a utility company and the amount displayed on the data centre’s water meter. Ideally water consumed by the data centre, or used to cool equipment, can then leave the data centre in the same form and volume, giving the ideal number of 0 for site WUE.

The second type is source WUE, which takes in a number of extra factors, mainly external from the data centre. It factors in how much water is used to create both electricity and gas at the utility company, as well as what is used internally, and with suppliers being hard to get accurate figures from, calculating source WUE can be tricky.

“Factors such as location, business strategy and financial constraints will determine whether increasing water use and decreasing energy use is the desired outcome, or whether higher energy use and lower water use is preferable (as in a desert location),” said Ovum.

There is still some way to go with WUE and the analyst firm claims new elements, such as water quality and water temperature, will come into play with later revisions, but it is an extra string in the bow of working out overall data centre efficiency.

Next from The Green Grid is CUE. The purpose of this metric is to measure the amount of greenhouse gas emissions comes from a data centre. The figure is calculated by taking the total greenhouse emissions and dividing them by the PUE or energy consumed by the data centre.

Ovum admitted that in areas where carbon emission recording was not written into legislation, the idea of using CUE may be viewed as “premature”.

However, it claimed, regardless of regulatory necessities, real business value could be discovered by reducing the carbon footprint.

“An enhanced corporate profile is an obvious potential benefit, particularly for industries where a “green” corporate image can influence consumer choice,” said the analyst report. “But, in other industries where corporate profile/carbon usage is not a high priority, CUE still can provide clear business value.”

“Data centres are like factories in that the energy they consume powers essential IT operations, just as machinery makes physical products. By minimising energy and resource consumption and operating efficiency, organisations can minimise the total cost of ownership and operating overhead.”

By adding these two metrics, The Green Grid believes it can really make a difference to how data centres run and its goal is a simple one.

“The CUE and WUE metrics enable data centre operators to quickly assess the water and carbon sustainability aspects of their data centres, compare the results, and determine if any energy efficiency and/or sustainability improvements need to be made,” said a statement from the organisation.

Although WUE and CUE are the two metrics that seem to be picking up momentum in the industry, there are three others The Green Grid hopes will be adopted too.

Data centre compute Efficiency (DCeE) and Server compute Efficiency (ScE) do essentially what they say on the tin and drill down further into the performance of hardware, rather than the productivity.

The point behind them is to help business get the most out of performance out their compute whilst still staying efficient within the entire data centre environment. However, Ovum warns that to calculate both metrics you need to work out the primary and secondary requirements.

For example, the data centre has one primary service, keeping the business workload running. However, whilst this is the main function of a server, it may also have secondary roles. A server may be used for email, but it may also have backup, virtualisation tools, virus protections etc, all secondary services to support the major function.

“ScE determines the proportion of work that provides primary services, which is then aggregated to determine the compute efficiency of the entire data centre (DCcE),” explained Ovum. “Organisations can then identify systems that are not being utilised.”

While these two measures provide a number for performance, the productivity of a server needs an extra metric. This is where Energy Reuse Effectiveness (ERE) comes into play.

Rather than just showing what energy can be reused within the data centre, ERE scores on what energy can be reused after it leaves the data centre. For example, whether the energy created by the heat from servers can be used to power other offices or even homes nearby the site.

The idea of using energy from data centres to power homes has been gaining traction over the past few years, with Microsoft sponsored research conducted by the University of Virginia in 2011 claiming the heat from racks could replace water and room heating.

This is the first time an organisation has tried to measure the achievement, however.

“Productivity metrics that can measure the usefulness of the work being done by IT gear within a data centre are the Holy Grail of data centre efficiency measurement,” claimed Ovum.

“This is because all other metrics fail to link power usage to the usefulness of IT workload to business.”

The new raft of metrics, WUE, CUE, DCeE, ScE and ERE - coupled with PUE - can give a business a much stronger idea of how to get the most out of their data centre, whilst also allowing vendors to prove the worth of their products more effectively.

They key though is to not take a single metric and use it to define everything you do - something both businesses and vendors have been guilty of with PUE.

“Do not make a business decision based on one metric alone,” concluded the Ovum report.

“Data centres represent a multi-dimensional challenge and opportunity, and a dashboard of metrics is required for any semblance of accurate measurement as a means to a more efficient end.”

But is this new list exhaustive or do we need even more measurements to ensure a truly efficient data centre? The Green Grid thinks so and will be publishing additional metrics this year.

“We believe more are needed,” said Tipley. “There are emerging areas related to cloud computing, Smart Grid interactions, building labelling, recycling, sustainability and software efficiency that The Green Grid will focus on in 2012 and beyond.”

“We will continue to pursue better ways to measure data centre energy and productivity efficiency.”