Cooling the cloud

15-08-2012 - John Hatcher

Heat management is a perennial problem for managers of data centres; temperatures build steadily unless tackled by cooling units almost as power-hungry as the servers they seek to cool. New high power servers have increased the workload and cooling systems often struggle to keep pace with the increases in heat.

Where heat load exceeds the capacity of the cooling system, the effect on reliability can be catastrophic as overheating servers cease to function properly. Aside from problems for user companies who cannot access their data, the effect in terms of remedial action and loss of corporate reputation can be equally devastating.

This sits against a back-drop of a constant pressure to drive down operating costs; the rising cost of electricity and environmental concerns suggest that throwing more mechanical cooling into the heat-reduction equation may not be the answer.

In response to the challenge of providing the capacity and availability required by data centres while driving down running costs and emissions, Emerson Network Power, has developed the Liebert PCW cooling system, an advanced chilled water floor mount unit for precision data centre cooling. The system addresses the growing cost of cooling servers due to virtualisation or cloud computing and offers a reduction of up to 70% in operating costs, driving Power Unit Effectiveness (PUE) down to as little as 1.1 in the SmartAisle configuration.

Setting it apart from current solutions, the Liebert PCW cooling system features an  inner aerodynamic design that allows businesses to reduce data centre operational costs through a combination of meticulous redesign of the interior of the unit to promote better air flow and advanced technology. One of the features of the Liebert system is its newly developed chassis. Emerson Network Power engineers studied air flow within the floor mount unit and completely redesigned the internal components, including the coil angle, filters typology and all the elements that may impact the inner aerodynamics. Optimised inner aerodynamics is a key differentiator, reducing airflow resistance and promoting efficiency. With this aerodynamic design, Liebert is able to reduce the running costs of the cooling system with less energy and the EC Fan 2.0 and automotive-like high efficiency filters minimise noise.

Issues around the need to better control server heat have conspired to form something of a ‘perfect storm’, a fact acknowledged by Forrester Research in their September 2011 Report: ‘Power And Cooling Heat Up The Data Center’. The report says, “Driven by the confluence of rising energy prices, the immense scaling of cloud workloads, and continual pressures on IT budgets -- power and cooling have become even more critical issues than they were several years ago.”

Emerson Network Power has taken the innovative step of utilising a roof-mounted freecooling chiller to take advantage of the freecooling achievable through the utilization of the heat exchange offered by external air starting when the environment temperature is in the range of 20-23°C . In warmer weather, mechanical cooling takes up the slack to chill the water while Liebert iCOM control systems adjust settings to match workload, weather and time of day. 

Of course not all data centres are created equal and while the Liebert PCW is designed for medium and large data centres, it is also appropriate for small facilities as the cooling system can be applied to a perimetric cooling configuration in module from 30kW to 220kW and above. The scalable Liebert PCW system is suitable for facilities where physical redesign is not possible or where server rooms lack height or a raised floor. Liebert PCW comes as part of the SmartAisle cooling solution and can be configured in three different ways. Adjustable legs, fan modules separated from the heat exchange, multiple configurations of water pipes, pluggable electrical connection enhance this flexibility - crucial if you are a data centre manager who needs to install a new cooling system with minimal fuss.

In total seven pending patents for efficiency, performance and reduced operational costs have been generated from this single project, showing clearly that it is innovation rather than mechanical methods which is required to meet the challenge of cooling the cloud.