MPIO

Novell has a simple howto for MPIO. I also found more details and how to do failover tests.

I've heard that LVM manages physical slices by device name (/dev/sdX), not disk ID and that since multipathd increments device names (/dev/sdc becomes /dev/sdd) that LVM gets confused and requires a vgscan and vgchange -a y between a remount. I'll try for myself sometime.

Update QLogic has a forum post on failover and LUNs discussing the redundant devices and more information about what they mean.