A migration agent, which is part of a distributed storage network, identifies one or more data objects stored as sets of encoded data slices in a first storage pool, and determines, for each of those data objects, whether to migrate corresponding sets of encoded data slices from the first storage pool to another storage pool. For at least one of the data objects, the migration agent determines to migrate a set of encoded data slices, and issues a set of MoveSlice requests to storage units included in the first storage pool, from which the data slices will be migrated. In response to the MoveSlice requests, the migration agent receives MoveSlice responses from the storage units in the first storage pool. If a threshold number of favorable MoveSlice responses is received, the migration agent facilitates deletion of the migrated encoded data slices from the first storage pool.