Green IT & Green Hosting

Staying Cool - The Hot Topic

07/11/11

Green IT Magazine Editor Brian Wall takes a trip up the aisle at iomart Hosting's City of London Data Centre to see how this company is meeting the demand of increased computing power with greater energy efficiency.

Take a tour through the four data halls in iomart Hosting's City of London data centre and you really do blow hot and cold. The use of alternate hot and cold airflow management systems means you detect a noticeable change in temperature from one aisle to the next.

Halfway along the largest data hall of the data centre are several black enclosed cabinets with sliding glass doors and glass ceilings. These are the result of the managed hosting company's introduction of cold aisle containment, which has taken place over the past two years.

The adoption of cold aisle containment by iomart Hosting is not just an example of a company embracing the latest developments in cooling technology for the sake of it. It stemmed from a dual need to meet new customer demands for high density computing, without putting their hosting services at risk, while at the same time maximising energy efficiency.

COOLING DEVELOPMENTS

"Conventional means of cooling in many data centres means that, in order to maximise the utilisation of available data floor space, you often need to limit the power delivered to each rack," says Paul Jeffrey, director, technical services for iomart Hosting.

"Limiting power in this way also restricts the number of devices it can hold, and therefore its profitability to the data centre provider and indeed its usefulness to the customer. As hardware manufacturers squeeze ever more processing power into smaller server sizes, the iomart technician works in a cold aisle pod 2 requirement for higher rack power and server density caused us to look at several developments in cooling.

"Before making any decision, though, we needed to ask three important questions of ourselves, our data centres and, of course, our customers. The questions we asked were: what does it allow us to offer to our customer base and will they benefit? What are the risks, if we decide to adopt it both for the data centre and our customers? And, finally, will it enable us to manage our energy more efficiently? The answers in all those scenarios were a positive endorsement of us introducing cold aisle containment."

COLD AISLE PODS

Cold aisle containment encloses racks of servers into what are called cold aisle pods. Ambient air in the main data hall of the data centre is fed from the computer room air conditioning (CRAC) units, creating cold air, which is then pumped in through an under floor or in-rack system to create a pressurised zone. The only way the cold air can move is through the servers, causing the fans to rotate more slowly. This results in greater overall efficiency, because less electricity is used in the servers, meaning more servers can be put in each rack.

Conventional cooling options, such as DX and chilled water solutions, were also considered by iomart Hosting, but were felt to be uneconomic, less efficient and carried a greater risk. For example, pressurised water pipes carry the risk of leakage and require additional space for the installation of fans and electrical equipment.

"For us, cold aisle containment involves no retro-fitting or major modification of the existing data centre infrastructure," states Jeffrey. "It's also very straightforward and highly efficient.

By enclosing the cold aisle in a corridor and directing all the cold air from the floor upwards in to the front of the racks, none of the air escapes out into the upper void of the data centre room. You're re-using the air and reducing carbon emissions as a result. It really is common sense and provides such a simple, non-intrusive solution. Importantly, our customers really like it, because it enables them to utilise higher density racks for their computing needs, without risk and with better power management."

Significantly, cold aisle containment is also relatively quick to install. iomart Hosting already used Rittal racks and chose the company to supply its cold aisle containment, too. Its on-site data centre engineers take between four to six weeks to install a customer into a cold aisle pod.

One big question remains, though. Do customers want it? Well, it seems that they do.
"Increasingly, we see customers asking for it," comments Sarah Haran, managing director of iomart Hosting. "I would estimate that 60% of our proposals now are for high density racks. Also, with our existing customers, if they need higher density computing we recommend they move into a cold aisle."

MASS MIGRATION

iomart Hosting now uses cold aisle containment in its data centres in London, Glasgow and Maidenhead. Around a thousand customers who were previously hosted in other London data centres have been migrated to Maidenhead as part of the company's purchase of Essex-based Titan Internet. All but a few have gone into cold aisle pods.

Once cold aisle has been installed, iomart Hosting has recorded an overall drop in temperature of at least 10 degrees Celsius. The Maidenhead DC alone is estimated to have saved 81 tonnes of CO2 emissions per month since installing it - times that by 12 and you have a huge reduction in its annual carbon footprint.

With data centres now being required to limit their environmental impact, cold aisle containment is obviously a big plus. Given that it is estimated that, for every megawatt of power used for the operation of servers, another megawatt is required to cool them, reducing the cooling power overhead is a key efficiency metric.

Haran continues: "As a managed hosting provider with our own data centres, we are definitely seeing the benefits to the efficiency of our computer room air conditioning units. This lessens our environmental discharges by reducing our carbon emissions, therefore improving our impact on the environment, while at the same time enabling us to meet the computing demands of our customers. It's a win-win situation. Power is necessary for us to grow our business, so we need more. However, we can mitigate our carbon emissions by using cold aisle and other positive developments in this kind of technology."

Cold aisle containment has only really been actively taken up in the last two years, but, as with all technology, it changes fast. So what's next on the agenda for the management of airflow?

Paul Jeffrey explains: "Numerous solutions are available to improve the efficiency of data centres, from a cooling and power consumption perspective. Unfortunately, many of them require major mechanical and electrical improvements to the data centre, which are potentially high-risk activities. We are constantly evaluating the potential energy efficiency solutions that are available on the market and will continue to do so, but we won't ever use new technology just for the sake of it. We will only use new developments that don't put the service we offer to our customers at risk."

"There's little point in taking networks offline or risking our continued operational stability just to install new technology. We are very careful how we install and there is always a huge risk factor that we need to mitigate. We would never do anything that jeopardises our 100% uptime guarantee."

Would there ever be a stage where iomart Hosting used cold aisle containment for all its customers?

"Not at the moment," responds Jeffrey, "because there will always be a demand from smaller customers that can be fulfilled by using 2kw racks. The beauty is that, at the moment, we can mix both technologies, without compromising what we do. We operate in a competitive market and we need to be using technology that satisfies our customers' requirements, whoever that customer is."

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