A method for execution by a dispersed storage and task (DST) processing unit includes determining to determine to overwrite an original data object stored in a plurality of storage units with an updated data object. Validation level data can be determined, where the validation level data indicates a data object overwrite level, a data region overwrite level, or a data segment overwrite level. Checksum metadata associated with the original data object can be retrieved in response to determining to overwrite an original data object. Overwriting of a subset of data regions or data segments of the original data object can be foregone in response to generating validation data that indicates their checksums in the checksum metadata compare favorably to corresponding overwrite checksum values.