1. A method for execution by one or more processing modules of one or more computing devices of a dispersed storage network (DSN), the method comprises: identifying a memory device having a first slice storage format (SSF) that is a legacy SSF to a second SSF within the DSN that includes a first encoded data slice (EDS) of a set of EDSs, wherein a data object is segmented into a plurality of data segments, wherein a data segment of the plurality of data segments is dispersed error encoded in accordance with dispersed error encoding parameters to produce the set of EDSs; when at least a predetermined threshold number of EDSs of the set of EDSs are included within one or more storage units (SUs) within the DSN excluding the first EDS of the set of EDSs, transitioning the first SSF of the memory device to the second SSF, wherein the first EDS of the set of EDSs having the first SSF is deleted during the transitioning; retrieving at least a decode threshold number of EDSs of the set of EDSs from the one or more SUs within the DSN; performing a rebuilding process using the at least the decode threshold number of EDSs of the set of EDSs to generate a rebuilt first EDS; and storing the rebuilt first EDS within the memory device to replace the first EDS of the set of EDSs having the first SSF that was deleted during the transitioning.