I would like to know how redundant ports (FED) work when one port fails.
For e.g. 1A and 2A are said to be in pairs/redundant ports. Will 2A take over if 1A fails? If we need the host to be zoned to both 1A and 2A to have redundant paths, why they are said to be in pairs? Cant we use 1A and 6B (any other port) to have same redundant configuration?
Although FED boards are installed in pairs, ports are not paired for redundancy. Your alternate path(s) can be on any other port(s) in the system. Some related advice, unless you have good reason otherwise: Do not create more paths than necessary for redundancy or performance (i.e. if you can get the job done with 2, don't use 8 just because you can). Use round-robin (all ports active). An HBA should not see more than one instance of any LUN (i.e. if you need 4 paths for a LUN, you should use 4 HBA, If 2 paths then 2 HBA)