Patent ID: 9575983
Date: 2017-02-21
CPC Classifications: G06F

Claim:
1. A method for calculating deduplication digests for a synthetic backup by a deduplication storage system using a processor device, comprising: constructing the synthetic backup by processing a plurality of metadata instructions provided by a backup application; locating stored data segments referenced by the synthetic backup; calculating deduplication digests of the synthetic backup based on stored digests of the referenced stored data segments; partitioning a data segment of the synthetic backup into fixed sized sub-segments, wherein each of the fixed sub-segments references multiple stored fixed sized sub-segments; aggregating the calculated digests of the synthetic backup sub-segments; forming the deduplication digest for the synthetic backup from the deduplication digests of all data segments of the synthetic backup; calculating the deduplication digest for each of the fixed sized sub-segments of the synthetic backup based on retrieved deduplication digests of the stored fixed sized sub-segments referenced by a synthetic backup sub-segment; calculating a threshold digest value from the retrieved deduplication digests; calculating a sub-set of candidate digest values from a set of retrieved digest values by including a digest in the sub-set if a value of the digest is one of equal to and larger than the threshold and a storage location of the digest is within boundaries of the synthetic backup sub-segment; arranging digests in descending order of values of the digests and selecting a first m digests if a number of the digests that are denoted as m in a set of candidate digests is one of equal to and larger than a required number of digests for each of the fixed sized sub-segments; and calculating the digests, based on data of the synthetic backup sub-segment, if the number of digests in the set of candidate digests is lower than m.