obtaining information by the data migration node, {HEAD ~ the information} identifying the first storage and {TAIL ~ the second storage} 
identifying
obtaining information by the data migration node , { HEAD ~ the information } identifying the first storage and { TAIL ~ the second storage }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL