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: distributedly storing a set of encoded data slices in an original plurality of storage units of the DSN associated as a current generation of a storage vault based on a current generation mapping of the set of encoded data slices that specifies the original plurality of storage units of the DSN, wherein the original plurality of storage units of the DSN includes a width dispersal parameter of a dispersed storage error encoding function by which the set of encoded data slices is generated; determining whether utilization of the original plurality of storage units is greater than a utilization threshold; when the utilization of the original plurality of storage units is greater than the utilization threshold, updating the original plurality of storage units to include at least one additional storage unit and a proper subset of the original plurality of storage units associated with the current generation of the storage vault to generate an updated plurality of storage units associated with a next generation of the storage vault, wherein the updated plurality of storage units includes more than a width dispersal parameter number of storage units; and distributedly storing the set of encoded data slices in the updated plurality of storage units of the DSN associated as the next generation of the storage vault based on a next generation mapping of the set of encoded data slices that specifies the width dispersal parameter number of storage units of the updated plurality of storage units that includes the at least one additional storage unit and excludes at least one of the original plurality of storage units of the DSN.