Data centre management is all about power and cooling - most data centres seem to have the data side of things sorted. It's the energy draw that hurts the budget most.
Well, that's close to the truth, close enough for our purposes. For years, idea that it took a watt of cooling per watt of power for computing has been a given. The standard metric is Power Usage Effectiveness (PUE), with a PUE of 2.0 indicating cooling and power distribution use the same amount of power as the computers themselves.
But many companies seem still to be - not quite, but almost - intensely relaxed about this one-to-one ratio.
Yet the spotlight has swung round in recent years such that its focus now is on energy costs. As well as buying more energy-efficient kit, a number of ideas are floating around, including natural air cooling, smarter siting of data centres in cooler climates or near renewable energy sources, more use of techniques such as computational fluid dynamics to model airflows within data centres, greater use of sensors, and more attention being paid to the location of servers: you don't put the big iron at the top of the rack where rising heat cooks it before it starts doing useful work.
Many data centres have taken up one or more of these. But few data centres publish real-world figures to show how those initiatives have changed energy consumption.
Google has. In a blog entitled Data Center Efficiency Measurements, Google has measured the energy input at the power utility end of its data centre facilities and compared it to the useful work produced by the computers inside.
The result makes interesting reading - especially when the blog claims that it should be possible for a data centre with "advanced efficiency solutions" to attain a PUE of 1.2; Google reckons it'll hit that target by 2011.
Google's not alone in this: arch-rival Microsoft reckons it's on target to hit the same mark at around the same time.
The point is that more companies need to publish their PUEs so their customers can make informed choices. Let's find out who really is as green (insofar as complex, energy consuming devices full of rare metals can be slightly be described as 'green') as they claim. Perhaps the reason they don’t is that they'd hate the competition, their customers, or even government agencies to find out just how inefficient their facilities are.