xenserver rescan fiber channel HBA target / LUN list

ssh or use xsconsole command interface,

use following command  to rescan Fiber Channel HBA target / LUN ( in my case, we use Qlogic fiber card for Xenserver 5.6)

echo "- - -" > /sys/class/scsi_host/host1/scan

where host1 will depend on which HBA channel used.