Optimistic locking in a distributed file system replication environment

Described is optimistic locking in a distributed file system replication environment, in which a replica machine (e.g., a replicated file server) sends an optimistic lock to other replica machines when a file is opened for write access. Other replica machines that receive the optimistic lock prevent read-write opening of the file until the file is unlocked, thereby preventing many conflicts. Acknowledgements are not required by the locking replica. Of the reduced number of conflicts, many of those conflicts may be detected and thus handled before the file is closed, while conflicts detected after close may be handled via conventional conflict resolution techniques, e.g., last-writer wins.