Supplying high availability with a standard network file system

The design of a network file service that is tolerant to fail-stop failures and that can be run on top of a standard network file service is described. The fault-tolerance is completely transparent, so the resulting file system supports the same set of heterogeneous workstations and applications as the chosen standard, To demonstrate that the design can provide the benefit of highly available files at a reasonable cost to the user, a prototype has been implemented using the Sun NFS protocol. The approach is not limited to being used with NFS and should apply to any network file service built along the client-server model