A dispersed storage processing unit selects a slice length for a data segment to be stored in a dispersed storage network (DSN). The data segment is encoded using a dispersed storage error coding function to produce a set of data slices in accordance with the slice length. A storage file is selected based on the slice length. A storage file identifier (ID) is generated that indicates the storage file. A set of DSN addresses are generated corresponding to the set of data slices, wherein the set of DSN addresses each include the storage file ID and a corresponding one of a plurality of offset identifiers (IDs). The set of data slices are written in accordance with the set of DSN addresses. A directory is updated to associate the set of DSN addresses with an identifier of the data segment.