Abstract

A system uses prevent and detect mechanisms to enable rewritable data storage media to be operated as a written-once-only media. A physical indication of the media casing serves as an indicator of the write-once-only status of the media. A watermark is magnetically recorded on the media at the factory with a portion of the mark detectable by the system and a portion only detectable by returning to an inspection station for verification. This protects against a complete erasure of all data from the media. A segment write status indication serves to indicate the write-once-only status of each segment of the written data. A portion of the written region, such as the preamble or control field of each segment, contains a status mark written randomly within the area as a status indication that the data was written once or multiple times within that segment. Three status mark areas in each segment write status region provides the minimum space overhead for achieving the desired degree of protection against overwrite or a pattern repetition.