IBM EXP15 Hardware Maintenance Manual

Also see for EXP15: Installation and User Handbook

Netfinity FAStT EXP500 loop redundancy: TheNetfinity FAStT EXP500 expansion unit provides redundantloop support. This redundant loop support is availablewhen the second ESM board is configured (as shown inthe figure below). If an ESM board, cable, or GBIC failson a loop, the second loop provides an additional measureof redundancy (that is, an alternative path to your diskdrives).Some FC controllers might not support loop redundancy.IBM Fibre Channel (FC) disk drives are dual-ported,providing individual access from two FC loops to the samedisk drive. When configuring the ESM boards, configurethe second ESM board the same way you configured thefirst ESM board. Refer to your controller documentationfor more information on dual-loop support andimplementation.Loop BinterfacecableInput OutputESM board CRUThe GBIC ports are labeled with an (input) and an(output). Some controllers might provide additionalreliability features if an (input) port is connected to an(output) port. As you daisy-chain Netfinity FAStT EXP500expansion units together, connecting (input) ports to(output) ports can facilitate reliability. In many cases, aloop will still function properly without attaching the(input) ports to (output) ports. Refer to your controllerdocumentation for requirements on connections betweeninput and output ports.A lit Bypass indicator next to a GBIC can be caused by anumber of things. It does not necessarily mean that theGBIC has failed. Refer to “Symptom-to-FRU Index” onpage 71 for other possible causes. If you do determinethat a GBIC has failed, follow the procedures below toreplace the failed GBIC.1. Check the software documentation provided with yoursystem for instructions on GBIC failure recovery96 IBM Netfinity EXP15, EXP200, EXP500 HMM