11. A delta compression system, comprising: a delta processing module to delta compress a first set of data chunks; and a cache to store a second set of data chunks; a data storage system to store a third set of data chunks; a preferential selection module coupled to the cache, data storage system and delta processing module, the preferential selection module to identify a candidate to serve as a base chunk for delta compression by ranking a set of candidate base chunks from the second set of data chunks and third set of data chunks by location status information that indicates a location and a compression status of a candidate base chunk then tie-breaking a ranked set of candidates by degree of similarity, wherein the location status data indicates the location and status of the candidate data chunk as in any one of a compressed in a cache status, a decompressed in a cache status, or a compressed in a data storage status, and wherein ranking the set of candidate data chunks using location status data for each candidate prefers a compressed in a cache status over a compressed in a data storage status.
11. A delta compression system, comprising: a delta processing module to delta compress a first set of data chunks; and a cache to store a second set of data chunks; a data storage system to store a third set of data chunks; a preferential selection module coupled to the cache, data storage system and delta processing module, the preferential selection module to identify a candidate to serve as a base chunk for delta compression by ranking a set of candidate base chunks from the second set of data chunks and third set of data chunks by location status information that indicates a location and a compression status of a candidate base chunk then tie-breaking a ranked set of candidates by degree of similarity, wherein the location status data indicates the location and status of the candidate data chunk as in any one of a compressed in a cache status, a decompressed in a cache status, or a compressed in a data storage status, and wherein ranking the set of candidate data chunks using location status data for each candidate prefers a compressed in a cache status over a compressed in a data storage status. 12. The delta compression system of claim 11 , wherein generating the sketch further comprises generating a set of features for the selected data chunk.