Method and apparatus for storing data in a reduced redundancy form. Binary Large Objects (BLOBs) are partitioned into subblocks according to a partitioning method, and the subblocks are stored in subblock clusters. Each BLOB is represented as a list of spans of subblocks which identifies a contiguous sequence of subblocks within a cluster. Storage redundancy can be reduced because the spans of two different BLOBs can refer to the same subblocks. An index may be used to map subblock hashes to subblock cluster numbers.