selecting at least some of {HEAD ~ the storage arrays}, a combined available performance capability of which is at least equal to {TAIL ~ the performance requirements} for the logical data volume 
selecting at least some of { HEAD ~ the storage arrays } , a combined available performance capability of which is at least equal to { TAIL ~ the performance requirements } for the logical data volume
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH