1. In a storage system comprising a plurality of different storage media divided into different partitions, a system for managing storage of an object comprising: a storage processor for determining a particular storage partition has reached a predetermined capacity threshold; a data migration processor for identifying within said particular storage partition an object to be moved and for identifying a target destination partition for said particular object in response to said capacity determination, said migration processor identifying said target destination partition based on one or more selected from the group consisting of (a) media type of said particular storage partition, and (b) information identifying related objects in said target destination partition; and a transfer processor for transferring data representing said particular object to said target destination partition.