DCN May 2016 - Page 21

design & facilities management employed, the type of IT deployed and local climate. As multiple data centres become more diverse in engineering terms, and come to be distributed across a variety of geographies with varying climates, managing all of these variables to optimise the energy consumption and efficiency of each data centre will become a greater challenge. The trend of data centres becoming more widely distributed geographically is a feature of edge computing: the evolution of data centres away from massive hubs at the centre of a global network, to smaller regionally based installations ever closer to the users of the data and applications housed within them. Among the trends driving this change are the emergence of the Internet of Things (IoT), in which embedded sensor driven network connectivity will connect all manner of physical devices. These range from buildings to automobiles and all manner of smart devices, collecting information to enable better business decision making. The growth of data intensive multimedia applications such as video on demand is also a key driver, accompanied by the growth in high definition TV services, which requires efficient management of high bandwidth networks at a regional as well as global level. Delivery of digital HDTV and video on demand requires service providers to locate their server farms close to their customers. Therefore viewers in London or Glasgow downloading the latest movie blockbuster to their TVs are likely to have a smoother, glitch free experience if the server farm is located in the UK rather than California. Lastly, the increasing demand for computing services in specialist applications such as mining and fossil fuel extraction, which typically takes place in remote or hostile environments, is driving the need for ruggedised computing applications. Congestion Edge computing is an inevitable consequence of vastly increased data traffic which requires more sophisticated traffic management. With the Internet of Things expected to comprise 50 billion devices connected worldwide by 2020, network latency and speed of response will require data transactions to be contained, as far as possible, within regional networks, to remove some of the congestion from global networks. Much effort has already been directed towards the challenge of using energy more efficiently in data centres. Vendors of data centre infrastructure equipment such as cooling, air conditioning, power supply and containment products have produced reference designs that allow highly predictable installations to be constructed. They make widespread use of metrics such as PUE to validate how efficiently a data centre’s power can be delivered to the IT equipment it contains. However, PUE is limited in terms of managing the overall energy consumption of a data centre, measuring only the relative difference between power consumed on IT equipment and that consumed on IT and infrastructure combined. So although it is now easier to build data centres with confidence that a low PUE rating will be achieved, it doesn’t automatically mean that overall energy consumption will be reduced. One strategy recommended by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) to reduce overall energy consumption is to arrange a data centre so that the ambient temperature inside can be allowed to rise. If a data centre can operate effectively at higher temperatures, the initial thought was that cooling equipment such as chillers can operate in economy mode and will not need to be deployed as frequently, resulting in a lower energy requirement. However, this technique has not been widely adopted for a variety of reasons. Apart from a natural conservative reluctance among engineers to change an approach that has been seen to work effectively, the results of allowing temperature to rise have been mixed. One size will not fit all for the many and varied data centres that will be built in the future. 21