HOW TO INCREASE
DATA CENTRE EFFICIENCY Nathan Tracy*
Cloud computing and bandwidth-intensive applications have made the data centre more important than ever, and managers want to squeeze every last bit of performance out of its architecture, even down to the connector level.
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n today’s environment, data centres are gaining importance due to the trend of outsourcing access to data (through the cloud) while continuously supporting bandwidth-intensive applications (such as video). Data centre managers want to squeeze every last bit of performance out of the data centre architecture, even down to the connector level. Five key criteria need to be considered when choosing input/output (I/O) connectors that maximise speed and efficiency in data centres — flexibility, cost, thermal management, density and electrical performance. These five criteria must also be optimised in the equipment’s backplane and power connectors.
Flexibility The I/O connector should offer maximum flexibility in the choice of cable type needed for each application. For example, suppose there’s a rack of servers that all connect to a top-of-rack switch. Most of these connections are fairly short — typically three metres or less — so it’s less expensive to use copper cable. But some connections may be longer and require optical cable. By using a pluggable form factor connector such as SFP+, SFP28, QSFP+ or QSFP28, the manufacturer gives the data centre operator the ability to choose the right cable to meet specific needs.
20 ECD SOLUTIONS - SEPTEMBER/OCTOBER 2015
Cost Based on industry trends, a server’s interconnect might be 1 Gbps, but in some of the more demanding applications servers now support 10 Gbps or even 40 Gbps. The 40 Gbps connections have been around for a couple of years, but the latest trend is to go to a 25 Gbps solution. The 40 Gbps solution implements four lanes of data at 10 Gbps each, so the manufacturer can build ‘intelligent’ equipment that can take the data, break it up over four lanes and then reassemble the stream into 40 Gbps. In contrast, 25 Gbps uses a single lane, so it has lower overhead and makes for easier implementation in the server and the switch.
Thermal management When you take a copper cable assembly and replace it with an optical module, the signal is converted from electrical to optical, so the module is now dissipating power. This may be less critical on a server where there are only one or two interconnects, but it’s a significant factor on a switch where there might be up to 48 interconnects. Thermal management becomes critically important because now the equipment has 48 little heaters adding to the heat already generated from internal components. With optical interconnects, manufacturers need to optimise for a new set of dynamics,
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