A method for enhanced block-level deduplication, the method comprising:storing one or more express block signatures in an express directory, the one or more express block signatures meeting a reference count requirement, the express directory implemented on memory;storing one or more primary block signatures and one or more reference counts for the primary block signatures in a primary directory, wherein each primary block signature has a corresponding reference count;computing the block signature of the data block as the data block is received by a storage device so long as resource usage of the storage device is below a resource threshold; anddetermining by a computer whether a block signature for a data block matches one of the one or more express block signatures stored in the express directory.
