when {HEAD ~ the data migration} from the first storage to {TAIL ~ the second storage} is completed, notifying by the data migration node the one or more network devices in the network that traffic that is received by the network devices is no longer to be routed to the data migration node; and 
when { HEAD ~ the data migration } from the first storage to { TAIL ~ the second storage } is completed , notifying by the data migration node the one or more network devices in the network that traffic that is received by the network devices is no longer to be routed to the data migration node ; and
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH