A dispersed storage unit within a dispersed storage network is configured with registry information including a slice name assignment indicating a range of slice names assigned to a vault associated with at least one user of the dispersed storage network. The slice names further corresponding to a plurality of potential data slices to be subsequently created and received for a pillar of the vault. The dispersed storage unit allocates a portion of physical memory therein to store the potential data slices based on the slice name assignment.