I thought I would share a multipath config file that worked out. SAN is HP P4000 (formerly LefHand) and is fairly common in HP environments. Unfortunately, the HP P4000 is not on the HCL for the newer 6.2 version of XenServer. It was last listed for XenServer 6 and 6.0.2, but only with iSCSI via a bonded network interface. I got lucky on the multipath config file by modifying the /etc/multipath.conf file with the following device entry:

device {
 vendor "LEFTHAND"
 product "P4000 disk"
 getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
 features "0"
 hardware_handler "0"
 path_selector "round-robin 0"
 path_grouping_policy group_by_prio
 rr_weight uniform
 no_path_retry 18
 rr_min_io 100
 path_checker tur
 prio alua
}

The above worked in Fibre Channel, where previously, only 2 of 4 paths were visible. Once the above change was made and multipath service cycled (service multipathd restart), we saw proper path detail, active ready and more importatnly active ghost on the failed paths. Previously, we saw failed for 2 paths. The next step was to detach the storage and reattach it via XenCenter. If you had running VMs, you would have needed to migrate the guests off of host 1 to host 2, and then locate the PBD for that host (xe pbd-list sr-uuid=<UUID of the SR> host-uuid=<UUID of the host>). Then you would do a pbd-unplug and pbd-plug. In XenCenter, you will then see 4 of 4 paths. I hope this helps other people who have HP P4000 and fibre channel connection.

Thanks to¬†Ariel M. for his patience. ūüôā