Crunching the numbers on data-centre efficiency

• Tags:
• Measure,
• Output,
• Saving,
• Consumption

Sally Whittle ZDNet.co.uk

Published: 20 Nov 2007 11:42 GMT

• 
• 
• 
• 
• 

...the servers themselves, said Titterington. "There's a figure on the box that says how many watts this thing uses, and you provision cooling and power on that basis," he said. "However, if you're only using two-thirds of the capacity, that's going to have an impact on the power and cooling you'll need."

One challenge when measuring the energy efficiency of servers is allowing for so-called "embedded carbon", added Andy Cox, a managing consultant with Morse. "There is energy associated with the design, manufacture and disposal of servers, so it's not simply a case of switching out all your kit for newer, greener models," he said. "In some cases, your overall energy costs might be lower if you keep an older machine for a while longer."

However, Shann pointed out that: "The biggest benefits often don't come from technology, but from people. So, if you consolidate servers, you may reduce management costs and thereby reduce the number of people commuting to the data centre. That's going to have an impact on energy and carbon."

The IT infrastructure is, of course, only a fraction of the overall energy picture in the data centre. The next biggest energy consumer is air conditioning and chilling — something that is virtually impossible to measure accurately unless you are building a new data centre with separate power supplies for cooling, says Titterington.

Some vendors are beginning to offer smarter cooling systems that should provide greater insight into their energy consumption. For example, HP recently launched its Thermal Zone Mapping offering, which measures existing conditions and predicts the effects of moving or adjusting cooling systems. The company has also developed a product called Dynamic Smart Cooling, software that can control the performance and output of cooling units more precisely.

After the IT infrastructure and cooling, the other major energy costs in a data centre will be due to UPSs (uninterruptible power supplies) and AC/DC conversion. Again, these may be difficult to accurately measure, but it should be possible to measure the energy requirements of such devices against their utilisation.

If this all sounds like too much hard work (and most analysts agree that an accurate energy audit is beyond the scope of most data-centre managers), an increasing number of vendors will crunch the numbers on your behalf.

BT offers customers a carbon-impact assessment, which is a vendor-neutral assessment of the IT infrastructure. IBM, meanwhile, offers an environmental-impact study that will analyse the end-to-end energy requirements of a data centre. An inspection by IBM Global Technology Services costs from $50,000 for a 30,000-square-foot data centre, the company says.

Most companies will be able to get a reasonably accurate impression of their energy ratings using a couple of days of consultancy, said Cox. "When we work with a client, we're looking at the life cycle of a piece of technology, and the complete cost of that," he explained. "We can then compare that with the benefit the company derives from a product in that specific context."

Cox agreed that the lack of standard calculations for this kind of assessment can lead to confusion, but he said he believes this is inevitable. "Personally, I don't think it's realistic to have industry-standard calculators for this kind of thing," he said. "There are so many different servers and platforms, each with different spin rates, different utilisations — it's impossible to measure that in a standard way."

• 
• 
• 
• 

• Share this article:
• Digg
• Slashdot
• Del.ici.ous
• Stumble
• Reddit