Expired files in the deduplicating virtual media are selectively erased using a backup application for notifying a backup repository of which expired files are no longer required. The space of the expired files is reclaimed for reuse. Virtual space of the expired files is reserved for allowing the backup application to seek past the reclaimed space to subsequent data in the deduplicating virtual media. Expired files are identified and positions of the expired files are determined in the deduplicating virtual media thereby converting the positions into a list of expired files that is sent to the backup repository.