The energy requirements of data centres have been growing at a rapid pace. As per the DatacenterDynamics 2012 Global Census on data centres, the power requirements of data centres worldwide grew by 63 per cent from 24 GW in 2011 to 38 GW in 2012. The census estimated a further 17 per cent increase in energy consumption to 43 GW in 2013. The rising energy demand has cost and environmental implications. Data centre managers and IT departments are therefore under increased scrutiny and pressure to deliver environmentally sound solutions at low costs.

 Heat and airflow management

 With technology advancements, servers are getting smaller, commoditised and, thus, cheaper. In order to make the best use of floor space, an increasing number of servers are being fitted into the same data centre. However, the prospect of too many cables crowding vertical managers poses a problem for thermal management in cabinets. Inadequate air circulation in the cabinet results in the deployment of data centre fans and cooling units for lowering temperature. Both these solutions consume additional electricity.

Blockage of airflow is an issue that arises on account of too many cables within the cabinet. This can be addressed by limiting the number of servers and cable terminations in a cabinet, especially in copper racks, where cables generally have a larger diameter. Another solution is to employ basic cable management within the cabinet, such as securing cables along the entire length of vertical managers for facilitating airflow. Integrated slack management systems can be deployed to locate and organise patch cords to ensure that maximum space is available for flow of cool air into and out of the cabinet. Using copper cables with smaller diameters is another solution to improve airflow within the cabinet.

Some possible solutions for airflow management include plugging unnecessary vents in raised-floor perforated tiles, plugging leakages in raised floors by sealing cable cut-outs, reducing air leakage by using gaskets to fit floor tiles more securely onto floor frames, turning off servers not in use, and managing heat sources directly by locating small fans near the heat sources of the equipment.

Emerging practices 

Having faced challenges related to the increasing number of servers and high density computing, organisations are realising the need for effective air cooling and heat management solutions. Some of these solutions are:

Liquid cooling

Liquid cooling systems utilise air or liquid heat exchangers to provide effective cooling and isolate equipment from the existing heating, ventilating and air-conditioning system. There are several approaches to liquid cooling:

•   Sidecar heat exchangers: These are closed enclosures that deliver cooling from the walls of the data centre, which keeps the cooling from dissipating into the server room.

•   Modular liquid cooling units: These are used within a fully sealed cabinet and are mounted at the rack base in a rack sidecar.

•  Integrated rack-based liquid cooling: This method incorporates rack-based architecture that integrates UPS power, power distribution and cooling. The architecture features a cooling distribution unit that pumps water through aluminium/plastic tubing to cool servers and other equipment.

 Hot aisle/Cold aisle layout

Adopting an alternating hot aisle/cold aisle layout is optimal and can correct many cooling problems in a typical data centre. Through the implementation of this layout, hot air recirculation can be avoided, which, in turn, eliminates the risk of an outage due to device failure. Moreover, a common hot aisle helps contain areas where heat density is high (such as racks with blade servers) and manages the heat in a case-specific manner.

 Virtualisation and consolidation

Research indicates that a server often utilises only between 5 and 15 per cent of its capacity to service one application. With appropriate analysis and consolidation, many of these low-utilisation devices can be combined into a single physical server, consuming only a fraction of the power of the original devices and saving costs. Virtualisation results in better application availability and business continuity, independent of hardware and operating systems, etc.

Reporting and compliance

In addition to optimising data centre power consumption, a green data centre solution framework should also provide reporting capabilities on an ongoing basis. For example, although it is not currently mandated, data centres may, in the near future, have to report their power usage effectiveness values, the carbon footprint of their equipment, EPA Energy Star rating, etc. Some countries such as Singapore and the US have already initiated this exercise.

In India, the Telecom Regulatory Authority of India has taken initial steps towards ensuring energy efficiency in the telecom sector by releasing its guidelines on “Green Telecom”. However, it may be a few years before these are fully implemented. Meanwhile, growing power costs and the increased pressure to reduce the carbon footprint is likely to drive the industry to optimise energy consumption.