communicating a status of the data migration by the data migration node to {HEAD ~ one or more other data migration nodes} responsible for managing {TAIL ~ data migration}, wherein the data migration node is an internal node of the network 
responsible for managing
communicating a status of the data migration by the data migration node to { HEAD ~ one or more other data migration nodes } responsible for managing { TAIL ~ data migration } , wherein the data migration node is an internal node of the network
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH