Efficient detection of discrepancies in multiple file copies

Summary.

For data consistency in distributed information systems, it is often necessary to compare remotely located copies of a file. We develop several protocols for the efficient detection of differing pages in a replicated file in different communication and failure models. The first set of protocols assumes a restricted but practical communication model. In this case, the minimum amount of communication necessary to identify any given number of differing pages is determined and a technique to attain this minimum is presented. For the more general communication model and for more refined failure models, we show that more efficient protocols can be derived. Our approach is based on the theory of Galois fields.