Serial data storage system with automatically adjusted data protection to implement worm media with limited overwrite allowing write appending

摘要

In a data storage subsystem, drive-level processing treats data storage media as WORM by automatically advancing a write append limiter as data is written, and preventing changes to data occurring before the write append limiter. Despite this media's WORM nature, the drive-level processing permits limited overwriting of data at the end of tape since the write append limiter lags the current write location by the margin of a write allowance index. Thus, despite the drive's treatment of the media as WORM, the drive permits overwriting of trailing metadata in order to facilitate write append operations.