Making your data centre greener

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Materials,
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Consumption

Jonathan Bennett ZDNet.co.uk

Published: 16 Jul 2007 16:33 BST

... the environmental restrictions in the country of origin are less strict than those in this country: Exporting your pollution isn't a solution. Buying servers manufactured closer to home, ideally in the UK itself, not only ensures they're made under tight environmental controls, but also saves the impact of transporting them by sea freight once they're made. You're also supporting the UK economy by buying machines made here.

3. Use virtualisation
Virtualisation can drastically reduce your need for physical hardware by allowing segmented workloads, normally run on different servers for integrity, to execute on the same machine without excessive overhead. VMware claims that its customers have typically been able to consolidate 12 servers into one for a given workload, which is a huge amount of hardware. In addition to the saving in server hardware, it also means you need less supporting infrastructure, such as cooling and network ports. This reduces further the amount of power needed to run your data centre.

Above and beyond the initial hardware savings you can get through virtualisation, it's also possible to get further power savings through moving virtual servers between physical boxes. When demand for services is lower, such as during the night, you can use a higher ratio of virtual-to-physical servers and power down the idle machines. This in turn produces less heat output, so your air conditioning will need to do less work.

4. Assemble your racks properly, and keep them that way
For cooling to work properly, you need smooth airflow over the components producing heat. This means you can't just put servers, switches and patch panels into racks any old how. The ideal rack configuration draws chilled air in from beneath, forces it through the equipment and vents it from the top. Leave the sides off your racks, or the doors open, or leave open spaces where rack space isn't used, and you destroy the smooth, fast airflow that rack fans are trying to provide. It may seem counter-intuitive to enclose equipment that's generating heat, but without proper airflow they'll heat up far faster — convection doesn't work well in a crowded rack. Ignore this, and your air conditioning will be working overtime, shortening the time between maintenance and using more electricity.

This means you need to keep the sides and back on every rack — even between racks that are side-by-side, and keep the door closed. This puts an end to the ad hoc network patch between racks, but you're heading for chaos if you need to use them for longer than a few hours anyway. Fit blanking plates where no equipment is fitted. Most importantly, make sure that there are fan trays in the top, bottom or both of each rack and that they're turned on.

5. Investigate green power sources
The simplest way to get green power is to find a supplier that uses only renewable sources. More of these are appearing on the market as time goes by, so do a little research into who's offering what.

You could go one stage further and invest in your own microgeneration facility. This could be wind- or solar-powered, depending on where you are in the country and the topography around your data centre. With the technology currently available it's unlikely this would be able to cover the entire power requirement for your data centre, but any mitigation of central, fossil-fuelled electricity generation improves your green credentials, as well as saving money in the long term. It's also a visible sign of your company's commitment to being environmentally responsible, which should make it easier to sell to the board.

There are many practical business reasons for increasing the energy efficiency of your data centre besides the altruistic ones. Energy costs may not yet be a major issue but availability is, and using less power gives you greater flexibility over where you can put your data centre. But being greener isn't just about energy, it's about the entire lifecycle, and you need to use your bargaining power as the customer to look after that. Make sure your supplier can meet your environmental expectations.