Mitigating the Effects of Optimistic Replication in a Distributed File System
Puneet Kumar · 1994
Optimistic replication strategies can significantly increase availability of data in distributed systems. However such strategies cannot guarantee global consistency in the presence of partitioned updates. The danger of conflicting partitioned updates, combined with the fear that the machinery needed to cope with conflicts might be excessively complex has prevented designers from using optimistic replication in real systems. This dissertation puts these fears to rest by showing that it is indeed practical and feasible to use optimistic replication in distributed file systems. It describes the design, implementation and evaluation of the mechanisms used to transparently resolve diverging replicas in the Coda file system. Files and directories are resolved using orthogonal mechanisms due to the difference in their structure and semantics. A server-based mechanism that uses operation logging is utilized to resolve directories, while a client-based mechanism that uses application support i...