D ATA CENTRE
How Cabling can Increase Energy Efficiency in Data Centres Current Affairs By Damien Simon, Data Centre Product Manager, Nexans Cabling Solutions
Whether they are planning a new build or refurbishing a current facility, data centre and network managers should be aware of the choices of cabling available to them and the energy efficiency benefits different types of cabling can bring.
There are a variety of trends affecting technology decisions for data centres and network infrastructures, including server consolidation, virtualisation, Moore’s Law and the need for greater processer power, and the increasing need for greater bandwidth to support interactive media, IPTV, mobile communications and high definition video-on-demand. Independent studies by Intel and Broadcom show that by 2017, 40G will have overtaken 10G as the standard rate of transmission required in data centres. Data centres are now critical to ensure that businesses stay competitive; throughput and latency are therefore key issues. However, perhaps the most
important issue facing the technology sector today is energy efficiency. In 2007, Gartner reported that the ICT industry accounts for the same
percentage of global emissions of CO2 as aviation; and collectively data centres consume more than 3% of Britain’s total grid power. Energy efficiency will continue to be
top of the agenda in the coming years so organisations need to plan effectively to ensure that they are as energy efficient as possible. The problem is that many data centre and network managers do not fully comprehend the difference that the network infrastructure can make on energy efficiency when considering their organisation’s technology requirements.
Fibre and copper cabling
The first consideration for managers is how to use fibre and copper cabling in their network infrastructures. Both materials have upsides and downsides: fibre is known to have the capacity to transmit high volume data at high speed over long distances, but is expensive and complicated to install in comparison to copper cabling. In addition, independent research at Penn State University using Cat 7A copper cabling has demonstrated that copper can support 40G at much greater distances than traditional twinax, with lower signal loss and superior immunity to noise over previous generations of cabling. An optimum solution would use fibre in the backbone with copper at
50 NETCOMMS Volume I, Issue 4 2011
the network edge. This is particularly important for the many organisations with large investments in legacy equipment, such as older, lower speed servers, which need to communicate with higher speed switches. Sustaining the life of balanced twisted pair at the data centre network will preserve this investment and avoid the upgrade to higher speed interfaces which are not required.
What grade of copper?
Data centre and network managers also need to take into account migration to higher bandwidth speeds to avoid future disruption and unplanned-for costs. Whilst data centres were previously intended to last for about ten years before being expanded or rebuilt they are now expected to last for 20 to 50 years, which means that specifiers need to consider the best cabling infrastructure in terms of longevity as well as energy efficiency. Since Cat 6A is limited to 10G, the lifespan of such an investment would only be 5-6 years before an upgrade is required. The highest grade of copper cabling
currently available is Cat 7A. This allows organisations to future-proof their network infrastructures so they have a longer shelf life. By doing this, they will have the ability to move from current bandwidth rates of
10G to expected rates such as 40G without requiring refurbishment or re-installation, thus reducing the energy use and costs incurred in additional construction work. Cat 7A has additional benefits
for organisations in terms of energy efficiency and return on investment, such as the increased benefits of short- reach mode. It uses individually shielded pairs of cables meaning it is less affected by alien crosstalk and internal noise and therefore needs less noise cancellation. The amount of power needed for the transceiver is therefore reduced. In the past, too many managers
have made decisions about cabling infrastructures based purely on cost at point of purchase but many are now realising the additional benefits available through higher grade cabling and the reduced total cost of ownership over the long term.
Energy efficient Ethernet
Using copper cabling at the network edge also allows organisations to take advantage of the benefits of Energy Efficient Ethernet (EEE) such as Wake- on-LAN, which uses the auto-negotiation capabilities that are only available with copper. This technology enables devices to be switched off when idle and assigns two watts of residual power to the NIC to listen for a ‘magic packet’.
Return on investment from better cabling.
www.netcommseurope.com
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