1. A method for secure data migration within a dispersed storage network (DSN), the method comprises: identifying a candidate dispersed storage (DS) unit of the DSN, wherein data objects are divided into data partitions in accordance with a data partitioning protocol and the data objects are stored as sets of data partitions in a set of DS units that includes the candidate DS unit; in response to a data migration request, receiving a migration receptiveness message from the candidate DS unit, wherein the migration receptiveness message includes an indication of availability to receive migrated data and a reported storage utilization for storing a first sub-set of data partitions of the sets of data partitions; in response to a data migration reference message, receiving, from another DS unit of the set of DS units, a migration reference response that includes an indication of storage utilized by the other DS unit for storing a second sub-set of data partitions of the sets of data partitions; determining a storage utilization of the candidate DS unit for storing the first sub-set of data partitions based on the migration reference response and the data partitioning protocol; and when the determined storage utilization compares favorably to the reported storage utilization and the indication of availability to receive migrated data is favorable, enabling transfer of data partitions of other data objects from a DS unit of another set of DS units to the candidate DS unit, wherein determining that the indication of availability to receive migrated data is favorable by: ascertaining storage capabilities of the candidate DS unit; determining other storage obligations of the candidate DS unit; determining available storage of the candidate DS unit based on the storage capabilities, the other storage obligations, and the reported storage utilization; and when the available storage compares favorably to a storage availability threshold, determining that the indication of availability to receive migrated data is favorable.