Perhaps a silly question this one, but I was wondering if it were possible to multipath a storage array across a FC connection and an iSCSI connection? Given that the main point of multipathing seems to be to increase resiliancy in the face of hardware failure, it seems logical that providing a storage pathway that depends on networking hardware would be a suitably resiliant alternative to a pathway that relies on FC.
I appreciate that the performance might not be the same across both, but might this not be an acceptable low-cost solution where there isn't enough budget for multiple FC connections (and fabric)?
Best Answer
theoretically, if device-mapper-multipath detected the same LUN over an iSCSI link it would add it to the available paths, and then it's up to you to make sure you set the failover and IO directions to the right priorities. I do however doubt you will see the same presentation of the LUN, because I haven't seen any arrays that allowed exporting LUNs and targets based on the same block device pool. If you know of such a device, please correct me, since I obviously haven't seen every possible SAN out there