Block-level and hash-based single-instance storage

A system comprising:

• a storage manager configured to interface with an application, where the application is configured to identify data blocks according to a first set of identifiers for the data blocks, and where the storage manager is configured to access the data blocks on a storage medium according to a second set of identifiers for the data blocks;
• a first lookup table that indexes data block signatures according to identifiers from the first set of identifiers, wherein each of the data block signatures is derived from at least a portion of contents of a corresponding data block;
• a second lookup table that indexes identifiers from the second set of identifiers according to the data block signatures.

A computer readable storage medium having encoded thereon program instructions executable on one or more processors, the computer readable storage medium being at least one of an electronic storage medium, a magnetic storage medium, or an optical storage medium, where the program instructions are executable to implement each of:

• receiving a first address of a data block;
• retrieving a signature corresponding to the first address, wherein the signature is derived from at least a portion of contents of the data block;
• retrieving a second address corresponding to the signature.