Making your data centre greener

While IT may not rival jet travel for damage to the environment, there's plenty the industry could be doing to lessen its impact on the planet. The good news is that the process of making IT green has already started, but there's still a long way to go. It's not just about using less electricity, either.

Consumer PCs contribute the lion's share of greenhouse gas emissions, and corporate data centres are also significant energy users. But there is a growing industry trend, pushed by vendors such as HP, IBM and Sun, to make corporate server systems more energy efficient. The perfect green data centre would use only sustainable materials and a minimum of energy from renewable sources, and it would be completely recyclable at the end of its useful life. This dream has yet to be realised, but a combination of product research and careful management is helping to make it more of a reality.

A data centre affects the environment throughout its life, from manufacture to disposal. The specific elements that need to be taken into account in any environmental assessment are:

• Raw materials
• Manufacturing by-products 
• Embodied energy
• Transportation
• Energy consumption
• Heat output/cooling requirements
• End-of-life removal
• Recycling/disposal

The raw materials that go into a server range from metals, to plastics, to more exotic compounds used in semiconductors. Metals form the bulk of these, and it should be possible to use recycled supplies. Much of the steel and aluminium in a server may already come from recycled materials.

There are other chemicals used in the manufacture of IT equipment that don't end up in the machines themselves, such as solvents used in cleaning. Although these are unlikely to be discharged into the environment, since most western countries now have laws forbidding such activity, they still have to be produced and disposed of once exhausted. Eliminating the need to use them in the first place by using environmentally inert alternatives is greener.

The law is now much stricter on hardware manufacturers. The Restriction of Hazardous Substances (RoHS) directive, which controls the level of hazardous chemicals a product can contain, came into force in 2006, and the Waste Electrical and Electronic Equipment (WEEE) directive was finally fully enforced in July this year.

Before servers are ever switched on, the actual process of shipping them to a customer site has an environmental impact. If the machines are being manufactured in another country, then there's the additional energy needed to ship it to this country, which will almost certainly use fossil fuels. Green-minded IT purchasers should ask vendors where servers were originally manufactured, and how many intermediate journeys they'll make between the plant and the final data centre.

The most obvious impact a data centre has, and one that companies probably have the greatest imperative to control, is its power consumption. While there are power-saving features in most new servers, and some vendors are even bringing out lower power consumption models, the truth is that even when idling, servers still use a significant percentage of their full power requirement. Only by making sure servers are fully utilised can companies hope to improve their efficiency.

So what can you do to make your data centre greener? Here are a few suggestions.

1. Don't over-specify hardware
While it's tempting to get more processing power, network ports or cooling capacity than required, with a little planning it's unnecessary. If you find yourself needing more capacity in less time than it takes to deliver a new server, you haven't been keeping an eye on your utilisation properly. Not going overboard on the hardware is the single greatest environmental step you can take: a server you don't buy doesn't require raw materials, doesn't have any manufacturing by-products, doesn't need any energy to run it, and doesn't need disposing of.

As well as only buying as many servers as you really need, don't oversize other infrastructure such as air conditioning and uninterruptible power supplies (UPS). UPS in particular shouldn't be oversized since they contain lead-acid batteries that need careful environmental management at the end of their useful life. The temptation is to get a larger UPS — or a UPS with an extended battery — to get greater autonomy time (how long the UPS can support its load on batteries), but for the number of times you'll encounter a power cut of more than a few minutes, it's almost certainly not worth it. If you do need your systems to run for very long times in the absence of mains electricity, get a generator (and run it on biofuel).

2. Check your server manufacturer's environmental policy
While much of what's in a company's policy will be generic enough to be of little use, it should list any certification the company has qualified for, such as the ISO 14000 standards for environmental management. This is the only way you have any control over those first few points in the environmental checklist. Don't be fooled by "greenwash", either — phrases that talk about what the company would like to do or is seeking to do are worthless — you need to know what the company is doing right now.

You also need to check where your chosen server vendor will manufacture the machines you buy from them. If it's outside the EU, the chances are...

... 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.