Patent ID: 8874532

Claim:
A computer program product for maintaining data objects in a storage space, the computer program product comprising a non-transitory computer readable storage medium having computer readable program code embodied therein that executes to perform operations, the operations comprising: maintaining a chunk index having information on chunks in the storage space referenced in the data objects to provide deduplication of the chunks, wherein the chunk index includes a reference count for each chunk indicating a number of the data objects in which the chunk is referenced and a reference measurement representing a level of the data objects references to the chunk; incrementing the reference count for one chunk in response to including a reference to the chunk in one of the data objects; selecting one chunk to remove from the storage space based on a criteria applied to the reference measurements of chunks having reference counts indicating that the chunks are not referenced in one of the data objects in the storage space; and returning indication of the selected chunk to remove from the storage space.