designating anyone of the plurality of storage arrays as {TAIL ~ a primary device} of {HEAD ~ the CSA} 
designating anyone of the plurality of storage arrays as { TAIL ~ a primary device } of { HEAD ~ the CSA }
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD