1. A method of handling a Network Data Management Protocol (“NDMP”) backup or copy operation, the method comprising: receiving an original NDMP backup data stream from a client; modifying the received original NDMP backup data stream by performing one or more of the following modification procedures upon the original NDMP backup data stream: deduplication, encryption, and compression, wherein the one or more modification procedures creates a modified version of the NDMP backup data stream; storing the modified version of the NDMP backup data stream in stored chunks, wherein each chunk is addressable by a physical offset and a physical length, wherein each chunk represents a modified version of a contiguous subset of the original NDMP backup data stream, and, wherein the client associates a logical offset and a logical length with the contiguous subset of the original NDMP backup data stream that is represented by each chunk; and, for each stored chunk, associating the stored chunk with: the physical offset and physical length that permits addressing of the chunk, and, the logical offset and logical length that the client associates with the contiguous subset of the original NDMP backup data stream that is represented by the chunk.