Machine manager 610 knows a location of each rack within the networks and {HEAD ~ each machine} and {TAIL ~ the database} that is/are located within the rack 
Machine manager 610 knows a location of each rack within the networks and { HEAD ~ each machine } and { TAIL ~ the database } that is / are located within the rack
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH