A method and system for improving tape drive memory storage is provided. The method includes receiving, by a storage tape drive, a data stream for storage. The data stream is passed through a non-volatile memory device (NVS2) of the storage tape drive. The data stream is divided into adjacent variable length data chunks and a chunk list file including similarity identifiers for each of the adjacent variable length data chunks is generated and stored within a (non-volatile memory device) NVS1. Duplicate data including duplicated data with respect to a group of data chunks of the adjacent variable length data chunks is identified and deleted from the NVS2 of the storage tape drive such that the group of data chunks remains within NVS2. The group of data chunks is written to a data storage tape cartridge. Pointers identifying each data chunk and an associated storage position are generated and stored.