Tag Archives: LPI

Energy Efficient Fibre Channel and related cost savings

For years many storage environments have used both active-active and active-passive multipath (MPIO) access mechanisms to access storage arrays in a dispersed or linear method. On enterprise class storage arrays with global caches the active-active method is most often used while on modular arrays you’ll see the active-passive scenario often applied. Inherently this means that during absence of IO, whether being the passive path or due to total non-IO operations (ie. there is no application or operating system sending or receiving any data), the actual fibre-channel links are only sending IDLE or ARB(ff) fillwords to maintain bit- and word synchronization. This also means that both the sender and receiver are always up and thus use the same amount of power as where they transmitting data at full line-rate. Obviously this is a waste of scarce resources and this is what has been addressed in the new FC standards that are coming up. The FC framing and signalling standard will be enhanced to have traffic diagnostics determine if an SFP should be in full power operating power or in a power reduced mode. Below are the details including some cost-savings calculations.

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