An apparatus and associated methodology contemplate a data storage system having a removable storage device operably transferring user data between the data storage system and another device via execution of a plurality of input/output commands. A commonality factoring module executes computer instructions stored in memory to assign commonality information to the user data. A deduplication module executes computer instructions stored in memory to combine a plurality of files of the user data (user data files) with at least one file of corresponding commonality information (commonality information file), the combined files forming a sequential data stream.