Atomic accesses to replicated files in reliable distributed file systems

This paper proposes an efficient mechanism to preserve the atomicity of accesses to a single replicated file, which creates an illusion for each user that the file is dedicated for his own use. The mechanism achieves better efficiency and a higher degree of concurrency than general transaction mechanisms. The concurrency control of atomic accesses is based on the optimistic method. Compared with other distributed optimistic algorithms, our mechanism has the following advantages: (1) It is fully distributed. Neither a central site nor a central clock is used; (2) Read only atomic accesses require no validations and are never aborted; (3) No locks are applied on the file during the network-wide validation and commitment. Simulations have been done to compare our method with a locking method.