Wednesday, 8 April 2009

Metering the Data Centre

PUE, DCiE, what’s it all about? PUE is a metric developed by The Green Grid to measure Power Usage Effectiveness (PUE); DCiE (Data Centre infrastructure Efficiency) is simply the inverse of PUE reported as a percentage. OK, so now we are in recession. There are, and will be more, calls for spending cuts and more efficiency from existing hardware and our staff. PUE and DCiE can play an important part in this.

But where to start? As we are talking data centres, look at the power consumption. Or more accurately, look to see if you can look at the power consumption. It is amazing how many data centres and computer rooms, even the new builds don’t have metering installed to monitor power consumption. Data centres are estimated to contribute 3% of the CO2 emissions globally, yet the vast majority of data centre managers have no idea how much energy their facility consumes – let alone where to start making savings.

How do you get on with your company’s Facilities Manager? Ok, putting that aside, it’s imperative that there is a good working relationship between these vastly important departments (IT and Facilities) as these two hold the key to reducing energy consumption, and therefore costs, more than any other department.

Look at it from the Facility’s Managers point of view. He has little if any impact on what is installed in the data centre. All he or she will see is the monthly or quarterly electricity bills coming in with little idea of where to reduce costs, or indeed, where the costs are coming from. Keeping him/her in the picture is incredibly important.

With metering installed a whole range of other opportunities for savings is opened up. Chargeback for example. Facilities charge IT for power used, IT charge the business, whether on an application basic or per U basis. The method can be agreed, the important thing is that metering opens the doors to making the whole business aware of the true cost of powering the data centre. Metering at the rack or server level isn’t necessarily needed. That’s an additional expense and an overhead to monitor. Although it would be great, keep it simple to start.

Working together to install electricity meters to enable the PUE and DCiE to be calculated and logged on a regular basis is a start. It is also imperative to log your consumption regularly by taking meter readings and trending the power usage, what impacts it and what changes it.

How much will you save by installing these meters? Without proper metering, who knows?

Migration Solutions is a specialist computer room and data centre specialist offering independent advice on the design, build and operation of data centres and computer rooms. See our website at, or email us at

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