Larry Lamers, member of technical staff, office of the CTO at VMware and board member of The Green Grid and John Pflueger, technology strategist at Dell and technical committee member of The Green Grid tells Data Centre Management Magazine about its plans for the industry

The Green Grid, an industry consortium consisting of some of the most recognized companies in the information technology field, aims to rapidly provide vendor-neutral information and resources to help improve data centre efficiency. Following an aggressive schedule, the group has already begun work on its roadmap for understanding, measuring and, most importantly, improving energy efficiency in the data centre.

Many Challenges to Data Centre Power Efficiency Efforts

Power management is a critical concern for today’s data centre. Ever-growing storage and computing needs are requiring more and more energy. Cooling, lighting and other facility requirements also require electricity, sometimes more than the computers themselves. At one time, companies wrung their hands over how to get the real estate necessary to accommodate all those servers, but today, energy costs are beginning to replace space alone as a basis for decision making.

Many pressing issues are driving the growing awareness of data centre power consumption. The most pressing include:

• Total cost of power: More servers simply consume more energy, causing utility bills to become line items of note where they were once more or less ignored.
• Local cooling issues (hotspots): even data centres with theoretically adequate cooling systems can be brought down by hotspots, where the physical arrangement of servers allows local temperatures to rise to damaging levels. A better understanding of power management could alleviate these problems.
• Utility caps on power consumption: If power usage is capped, enhanced efficiency is an absolute requirement for growing capacity in the region controlled by the utility.
• Facility capacity concerns: Increasing the capacity of existing facilities is generally favored over expanding them or building new ones. One way to do that is to improve energy efficiency, allowing more work to be accomplished in the same amount of space.
• Environmental Awareness: Growing concern over the impact of energy consumption on our environment puts additional pressure on decision makers to give greater consideration to power management.

Despite these good intentions, improving energy efficiency in the data centre is a complex matter. Proprietary energy usage data are budgetary matters not widely shared. In fact, because the department that pays the electric bills may be entirely separate from the IT department, information on energy usage is often little-known or disseminated. Basically, until now, many IT decision makers simply didn’t care about the electric bills because they didn’t have to pay them. This makes sense if energy costs are minor compared to equipment costs. That will no longer be the case as hardware gets cheaper and energy prices rise. IT managers find themselves in a situation where they cannot support the future computing needs of their enterprise without substantial capital investment.

No commonly held, empirically validated set of power “best practices” exists today, leaving companies to approach the matter on an ad-hoc basis with predictable results. Even measuring the amount of power used by a given installation is challenging given complexities of determining energy consumed by computers compared to facilities. This is particularly true in cases where the data centre is housed in a mixed-use facility.

Managers need to know how they can increase energy efficiency immediately and what they should be looking to do in the coming years. They need information on how to retrofit today’s data centres and how to design tomorrow’s centres with efficiency as a central concern from the beginning. These activities require defining how to collect data on and quantify energy efficiency, and developing an understanding of how different operational and architectural decisions affect data centre efficiency.

To fulfill these aims, some of the world’s most significant IT companies have joined together to form The Green Grid, a global consortium tasked with improving data centre efficiency and promoting those practices and technological approaches that assist in that goal. The Green Grid’s mission includes defining models and metrics; creating technology and best practices to improve efficiency; and educating the industry energy efficiency. It provides a forum for discussion of energy issues and a place for consensus to be formed in order to present a unified voice to the world.

A Roadmap to Efficiency

The very phrase “energy efficiency” could have many interpretations. In the first stage of its work, The Green Grid is beginning with an efficiency metric—a way to measure how efficiently the facility’s infrastructure delivers power to its IT equipment. As the problems become better understood, they will promote the development of metrics that enable stakeholders to get more productivity out of their data centres per unit of power used.
To reach that ambitious goal, The Green Grid is taking a systematic approach. Their first mission—already significantly underway—is to better understand the situation by collecting data on standards and metrics in use today This will allow them to identify correct metrics and develop new ones where gaps exist. Once the right metrics are in place, the consortium will develop ways for data centre owners and managers to assess their data centre architecture and data centre operations. The tools they will create include reports on best practices and a cross-industry database of configuration and performance information. The third phase of The Green Grid’s work is to investigate and provide guidance on existing and emergent technologies that have the potential to improve data centre efficiency. Beginning with an overall technology efficiency roadmap, they will continue with analyses of power distribution configurations and cooling architectures.

Measure Properly

The Green Grid has already completed a number of deliverables. One of its most interesting work products is a couple of new metrics that will enable comparable, efficiency-centred power measurements.

One of the most common data centre statistics in use today is Data centre Density (DCD). DCD is defined as the power of equipment on the raised floor divided by the area of the raised floor. DCD gives an idea of installation density—but says nothing about how well that power is being used.
The Green Grid has a set of interrelated equations that are better measures of efficiency. The equations start with the basic idea of what constitutes efficiency. The assumption is to maximize the amount of power used to process data (compute, storage, network) and reduce the amount power used by non-computing equipment such as UPS, generators, PDUs and distribution losses external to the IT equipment.

The metrics are called Power Usage Effectiveness (PUE) and Datacentre Infrastructure Efficiency (DCiE). PUE is total facility power divided by IT equipment power. DCiE is the reciprocal of PUE times 100%.

The measurement of total facility power is taken at the power meter. In mixed-use buildings, it is important to measure only the power entering the data centre itself so as not to include unrelated power consumption for offices, elevators, and so on. Total facility power is the power used by the IT equipment itself as well as everything that supports it. This includes power delivery components like batteries and generators; cooling systems including chillers and cooling towers; waste from running UPS equipment at inefficiently low loads; and other support functions like lighting.

The IT equipment power is the power used for computing, storage and networking. The Green Grid includes switches as well as monitors and laptops used by administrators to interface with the servers as components of IT equipment power.

The initial metrics provide shorthand for data centre managers to quickly compare efficiency among installations. Once baselines are established, it will be easy to see where improvements need to be made. For instance, a PUE of 2.0 indicates that the facility power is twice that used to power the IT equipment. If the IT equipment in this example require 1,000 watts, the facility will consume 2,000 watts (assuming a linear relationship between IT equipment power and total facility power). DCiE in this case is 50 percent, so half of the data center’s power is consumed by the IT equipment.

How would a decision maker act on this information? Once benchmarks are available, they could decide whether and how to make changes to increase efficiency. In a perfect world the PUE would be 1.0, meaning 100% of the energy entering the data centre is powering the IT equipment. Initial work completed by The Green Grid shows that many data centres have a PUE of 3.0 or greater (meaning it takes three watts from the utility grid to produce one watt of IT equipment power). The organization believes that a PUE of 1.6 is achievable with today’s equipment and good design practices.
One of the next steps is to illuminate the standards—typical and target PUE/DCiE values for various data centre configurations that managers can use to make decisions. That information is coming.

Additionally, measuring power is not always a straight forward matter. It is often impossible to draw hard lines between IT equipment power and facility power, especially with the integration of cooling technology into servers and racks. To address these concerns, new measurement techniques are planned. Once measurement systems are in place, data centre owners can create benchmarks against which to measure the effectiveness of changes.

The Fast-Approaching Future

Clearly, the industry recognizes that energy efficiency has become a significant factor in data center design. Even without environmental concerns the business reality of the limitations of power availability and its cost force companies to take action. The reliance on data centres to meet critical business needs, our personal needs, and online public services give us an incentive to fix it. The success of The Green Grid to improve energy efficiency has ramifications world wide, for the environment and our everyday life as well.