FT-NFS: an efficient fault-tolerant NFS server designed for off-the-shelf workstations

In most modern local area network environments, NFS is used to provide remote file storage on a particular server machine. A consequence of this distributed architecture is that the failure of the server results in paralysis or a loss of work for users. The paper presents the design of a low cost fault tolerant NFS server which can be installed on most Unix networking environments. FT-NFS runs as a user process and does not necessitate any underlying specific operating system functionality. The originality of our approach relies on the use of a stable cache which provides data availability and resiliency to a single failure. The main benefits of the stable cache are first to allow disk write operations to be safely performed in the back ground and second to permit the gathering of small files in large containers. The latter technique permits disk I/Os to be improved by reducing their number and increasing their length. Under the nhf-stone benchmark, FT-NFS outperforms the in kernel Sun NFS implementation both in terms of latency and throughput.