Just for the occasion … Setting HBA queue depth length on HP-UX systems with an SCSI I/O control command:
scsictl -a -m ir /dev/rdsk/cXtXdX
delivers the current queue- depth on the questionable device cXtXdX, where the Xes refer to the IDs in your systems.
scsictl -m queue_depth=21 /dev/rdsk/cxtxdx
sets the queue-depth to e.g.21.
The value of your queuedepth depends on the supported values of your storage and are given in a range from 1 to 255. By chance these values may conflict or fit together and well result in dedicated HBAs in dedicated zones.
In my case they fit together by default with HP EVA and HDS VSP, keeping in mind that there are changes needed if the EVA systems have to handle extremely large single files within a single LUN.