A brief history of server cooling

Author: Sean McGrath

In order to keep up with advancements in data centre technologies, cooling strategies have evolved rapidly in recent years. Not long ago, most cooling models relied on 'chaos' air distribution with computer room air conditioning (CRAC) units pushing large volumes of cooled air across IT equipment and forcing warm air towards ventilation ducts. However, chaos air distribution suffers many inefficiencies such as recirculation and air stratification.

With data centre temperatures increasing as technology progressed, businesses turned to hot aisle/cold aisle rack arrangements. This configuration sees cool air intakes and warm air exhausts facing each other at each end of a server row. This generates convection currents, which helps to improve airflow. However, this configuration still does little to meet the demands of today's data centres. Similar to chaos distribution, air flows too freely to ensure adequate cooling.

This ultimately led to containment cooling methods in which air flows were designed to tightly control airstreams. Containers fully encase server racks which transfer warm exhaust air to perimeter CRAC units and then return cool air to the equipment.

This improves cooling efficiency by ensuring that the hot and cold air streams remain separated, eliminating all of the problems outlined above.

As well improving longevity of IT equipment, containment cooling lowers energy consumption by an average of 15 per cent. This is because return air does not need to be cooled as much as it is entirely compartmentalised and therefore does not mix with warm air.

Because the container cooling methodology does not rely on convection, server racks do not need to be aligned as they do in hot aisle/cold aisle rack arrangements. This allows businesses to be more flexible with their data centre layout.

Some manufacturers are now providing liquid cooled containers, which use a dielectric solution that improves the transfer of heat away from server components and further reduces energy costs by as much as 50 per cent.

For smaller deployments, climate controlled cabinets are able to adequately cool servers utilising the same fundamental principle as container cooling but on a smaller scale.

This can not only significantly reduce CaPex by negating the need for costly infrastructure such as compressors, air handlers and piping but can reduce OpEx because rather than unnecessarily cooling large spaces, air conditioned cabinets simply cool the servers.

Despite these advancements in server cooling, many businesses persevere with legacy strategies for designing a server centre. The building or structure is created and then saturated with server racks. This leads to inefficiencies across the board, from cooling to wasted space.

Rather than designing the space first and adding the server second, businesses should choose the servers that will suit business needs and then design the space around it in order to ensure that equipment is adequately cooled and easily accessible.