In a switched environment, make sure persistent FCIDs are configured on Cisco MDS and Brocade switches. Another issue with 11i v2 and earlier is the HP-UX disk device hardware paths reference the FCID of the target ports. So if you move your Pure target ports to another switch port and persistent FCIDs are not in place, you will lose access to your LUNs since the FCID would have changed. That means the hardware path to your LUN changed and HP-UX loses track of the device.