By Guest Bloggers - John Stanley and Ken Brill, the Uptime Institute

Meeting business IT objectives is the purpose of data centers

Data center energy efficiency is an issue worthy of executive-level attention because it is the key to controlling costs as the demand for IT services continues to grow. But despite the buzz, we in the industry should remember that the purpose of a data center is not to be energy efficient. The purpose is to meet a business need for the IT services that drive revenue, productivity, and customer satisfaction, all while meeting service level agreements for response time and availability.

That said, businesses should strive to deliver these IT services in the most energy-efficient way possible – minimizing capital outlay, operating expenses, and negative environmental impacts.

Executive focus solely on PUE can be misleading – IT efficiency is actually the most important part of the data center cost / investment / energy equation

Most industry focus and management attention has been on PUE, but to focus exclusively on PUE can be highly misleading. PUE is an excellent metric, but it tells less than half of the data center energy story. PUE tells a manager how much of the facility’s total energy makes it to the IT equipment, but it says nothing about whether the IT equipment uses the energy in a wise, optimal, or cost-effective way. It also says nothing about whether the data center is getting the most out of its capital-intensive IT and facilities assets.

For example, as mentioned by Emerson Network Power  and others, improved IT energy efficiency will clearly save energy and drive large savings in facility CapEx, but these benefits won’t be reflected in PUE. Imagine replacing standard pieces of IT equipment with more efficient models – ones that do more useful work per Watt consumed. The data center’s IT load will decrease, but the facility load will decrease, too, since the power conditioning and cooling systems don’t need to do as much work to accommodate the efficient devices. The PUE ratio is likely to get worse, since the facility equipment will operate less efficiently at lower loads. However, data center energy use has gone down significantly, and precious UPS and cooling capacity have been freed up for later IT load growth. These are clear benefits that PUE wasn’t designed to capture.

IT efficiency is sometimes cheaper and easier to improve than PUE

Furthermore, IT efficiency is sometimes cheaper and easier to improve than facility efficiency. Many factors that determine facility efficiency are “locked in” for the life of the facility – for example, location, reliability Tier level, and type of power and cooling equipment. Often, the only thing that facility managers can do is implement operational best practices within these constraints.

On the other hand, IT energy efficiency can be more flexible. Data centers buy new equipment and turn over old equipment frequently, so there are plenty of opportunities to make efficient choices with immediate impacts. Consolidating servers via virtualization or removing “comatose” servers can also save energy quickly. And unlike site infrastructure upgrades, these IT measures can be done with little or no facility downtime or CapEx investment.

Also, IT efficiency can potentially save more energy than facility efficiency. Think about it: If the facility PUE is 2.0, then every saved IT Watt actually saves two Watts total, by definition. There’s a multiplier effect for IT energy savings! (see the chart on page 3) More importantly, every IT Watt saved also frees up valuable power and cooling capacity for later use by new IT boxes, allowing a company to put off the day when it must make a major capital expenditure for a capacity expansion or new data center facility.

Caution – IT changes are not trivial

However, use caution when considering IT efficiency improvements – changes to IT practices are not trivial. IT shops do things the way they do because of the business requirement to meet service level agreements on response time and availability. For example, running only one application per server results in extremely poor utilization, but it keeps application crashes from propagating. Some idling servers really are “comatose” and should be unplugged, but other idle boxes are actually failover hardware waiting to save business continuity when disaster strikes. If you value your job continuity, it pays to know the difference.

Data centers that wish to make changes to IT in order to delay expensive capital upgrades, save on OpEx, or “go green” (or all three at once) should remember that these benefits must be sought in the context of achieving the data center’s business mission. Luckily, the opportunities for improvement are great. We should embrace efficiency improvements earnestly, but prudently.

Call to action – Mind your facility PUE, but mind your IT, too

So, IT energy efficiency complements PUE by telling the other part of the data center energy story. What now? Here are some recommended action items for data center managers and the executives who lead them:

• Keep striving to improve PUE, but remember that IT energy efficiency is equally (or more) important.
• Also, remember that measuring PUE for internal self-improvement is easy, but benchmarking against someone else’s PUE is hard. When benchmarking PUE against others, be sure that the comparisons are made on a consistent basis. 
• Tell your IT purchasing department to seek out more energy efficient IT hardware. When trying to justify the price premium, remember that you’re saving facility power and cooling capacity (big CapEx) in addition to electricity bills (smaller OpEx).
• Remember that even aside from energy, IT equipment and data center facilities are expensive capital investments that should be highly utilized. Data center managers should try to get as much useful work out of both as they can! 
• When doing cost-benefit analyses on potential new applications, make sure to count the Total Cost of Ownership (TCO) of the decision, not just the server price. Each “cheap” server also comes with an electricity bill and consumes some of your valuable power/cooling capacity.
• Consider appointing a data center “Energy Czar” within your organization to act as the point person for these initiatives. Having a single point of accountability can help break down the organizational barriers that have made it hard to manage energy in the past.