Patent ID: 8332575

Claim:
A data management system comprising a data processor configured to provide: a file system module configured to transfer file user data and file metadata that describes the file user data in block units; a flash translation layer (FTL) module configured to receive the file user data from the file system module and to store the file user data in a logical block of a flash memory; and a filter layer module configured to receive the file metadata from the file system module, to retrieve at least one block from a phase change random access memory (PRAM) corresponding to the logical block of the flash memory to which the file user data is stored, to compare the retrieved at least one block to at least one block of the file metadata received from the file system module to identify changed file metadata in the received at least one block and to store the identified changed file metadata in the block of the PRAM in sub-block units, wherein retrieving of the at least one block from the PRAM is performed in block units.