With HP-UX 11.31 0709 and 0803 hosts, a volume with SCSI LUN ID 0 must be defined in each I/O group for the remaining disks to be recognized.
By default, the lowest available SCSI LUN ID is allocated when a volume is mapped to a host; for example, 0 for the first host mapping. A volume can also be created manually such as in the following example of defining a volume to host mapping with SCSI LUN ID 0:
mkvdiskhostmap -host host_name|host_id -scsi 0 vdisk_name|vdisk_id