Abstract: A method and system of optimizing the memory usage and performance of data deduplication storage systems includes organizing the metadata of data blocks needed by deduplicating storage systems. A three level hierarchy is used. Level 1 stores the metadata on disk along with the user data. Level 2 uses low latency storage (e.g. RAM and Solid State Disks) to cache the on-disk meta data for faster direct access. Level 3 organizes the fingerprints using a Trie and is entirely resident in RAM. Thus, the search, to determine whether a data block is unique or not and a candidate for transfer, can be more efficiency executed and to ensure that the meta data is transactionally secure.