Patent ID: 9542413
Date: 2017-01-10
CPC Classifications: G06F

Claim:
1. A stored-data deduplication method for eliminating a duplicate data fragment from a storage area in a storage device, the duplicate data fragment being a duplicate of one of data fragments constituting data stored in the storage device, the method comprising: dividing the data to be stored in the storage device into the data fragments; recording the data by using configurations of the divided data fragments; judging whether identical data fragments exist in the data fragments; when it is judged that the identical data fragments exist, storing one of the identical data fragments in the storage area of the storage device, and generating and recording data-fragment attribute information which is information indicating an attribute unique to the data fragment stored; upon receipt of a request to read the data stored in the storage area of the storage device, acquiring the configurations of the data fragments forming the read-target data, reading the corresponding data fragments from the storage area of the storage device, and restoring the data; acquiring and coupling the recorded data fragments to generate concatenation target data targeted for judgment on whether chunk concatenation is possible or not, and detecting whether the concatenation target data has a repeated data pattern which is repetition of a particular data pattern; and using as a concatenated data fragment a sequence of a plurality of the data fragments having the detected repeated data pattern, generating from the concatenated data fragment concatenated-data fragment attribute information indicating an attribute of the concatenated data fragment, and recording the concatenated-data fragment attribute information, wherein the repeated data pattern is not recorded when the number of times the repeated data pattern is detected is less than a predetermined value, and wherein when the detected repeated data pattern contains a plurality of the identical data fragments, the repeated data pattern is divided to avoid having the identical data fragments.