Controlling the Chunk-Size in Deduplication Systems

A special case of data compression in which repeated chunks of data are stored only once is known as deduplication. The input data is cut into chunks and a cryptographically strong hash value of each (different) chunk is stored. To restrict the influence of small inserts and deletes to local perturbations, the chunk boundaries are usually defined in a data dependent way, which implies that the chunks are of variable length. Usually, the chunk sizes may spread over a large range, which may have a negative impact on the storage performance. This may be dealt with by imposing artificial lower and upper bounds. This paper suggests an alternative by which the chunk size distribution is controlled in a natural way. Some analytical and experimental results are given.