Patent ID: 8392791

Claim:
A data storage system comprising: a plurality of storage devices arranged in a redundant array; a storage system controller for controlling data and redundancy data stored to and read from the storage devices such that the data is stored at least in part by striping the data into a region that comprises storage areas on at least two of the storage devices and such that the plurality of storage devices appear as a single storage device to an entity external to the data storage system, the storage system controller comprising: a redundancy data generator operative to generate the redundancy data for the data, the redundancy data suitable to reconstruct a lost or damaged portion of the data based upon content of the redundancy data and a remaining valid portion of the data; a de-duplication fingerprint definer operative to define a portion of the redundancy data as dual purpose data that additionally represents a de-duplication fingerprint for the region, where the portion of the redundancy data that is defined as dual purpose data was created in the same operation that created the redundancy data, and where the portion of the redundancy data that is defined as dual purpose data is error correction code (ECC) data; and a data de-duplicator operative to identify a duplicated region based upon finding a match to the de-duplication fingerprint within the redundancy data of the data storage system.