Yesterday, we got multipath working with our HP MSA1500cs SAN. We have a fully redundant setup with redundant controllers, fibre channel switches, and two FC controllers per host.
We had been having a lot of trouble getting things to work right with active/passive controllers. We could get failover to work in some cases, but getting everything to communicate correctly in the event of a failure was difficult, since every machine would have to flip over to the passive controller simultaneously.
With a firmware upgrade, the MSA 1500cs can support active/active controllers. With the dual-active setup, both controllers are active simultaneously and both are valid paths.
Despite HP support’s indications to the contrary, HP does have information on using built-in multipathd in Linux instead of their proprietary multipath solution. It’s document c00635587, part AA-RW8RA-TE.
We’ve configured multipathd.conf like this:
path_grouping_policy multibus path_checker tur failback immediate no_path_retry 60 path_selector "round-robin 0"
Just put that in your default block and it should work.