Patent ID: 8578112

Claim:
A data management system comprising: a server for writing and reading data blocks in response to a request from a host system and managing storage and retainment of the data blocks; and a storage system for storing and retaining management information for storing and managing the data blocks in response to a request from the server; wherein when the server stores and manages the data blocks in the storage system based on the management information stored and retained in the storage system, the server manages the data blocks by dividing each data block into a plurality of chunks, extracting any chunk as a judgment chunk from the plurality of chunks obtained by dividing the data blocks, and grouping the data blocks based on the extracted judgment chunk; the server executes deduplication processing for eliminating mutually duplicate chunks on a plurality of data blocks belonging to the same group, gathers a plurality of chunks belonging to the same group after the deduplication, and manages them as a chunk data set; if a data block deletion request is issued from the host system, the server judges, based on the number of times of references of a chunk data set corresponding to a group of the data block for which the deletion request was made, whether or not the chunk data set should be a target of garbage collection; and if the chunk data set is determined to be the target of garbage collection, the server copies only chunks of the data blocks, which are not deleted, among the plurality of chunks constituting the chunk data set to a temporary area at some timing, creates a new chunk data set by gathering a plurality of chunks composed of only the chunks copied to the temporary area, and manages the created new chunk data set by replacing the existing chunk data set with the created new chunk data set.