wherein any of the storage arrays may take over as the primary device in {HEAD ~ response} to sensing a failure of {TAIL ~ the primary device} 
wherein any of the storage arrays may take over as the primary device in { HEAD ~ response } to sensing a failure of { TAIL ~ the primary device }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL