Abstract

The 4.4BSD implementation of the Network File System (NFS) 1 is intended to interoperate with other NFS Version 2 Protocol (RFC1094) implementations but also allows use of an alternate protocol that is hoped to provide better performance in certain environments. This paper will informally discuss these various protocol features and their use. There is a brief overview of the implementation followed by several sections on various problem areas related to NFS and some hints on how to deal with them. Not Quite NFS (NQNFS) is an NFS like protocol designed to maintain full cache consistency between clients in a crash tolerant manner. It is an adaptation of the NFS protocol such that the server supports both NFS and NQNFS clients while maintaining full consistency between the server and NQNFS clients. It borrows heavily from work done on Spritely-NFS [Srinivasan89], but uses Leases [Gray89] to avoid the need to recover server state information after a crash. 1. NFS Implementation The 4.4BSD implementation of NFS and the alternate protocol nicknamed Not Quite NFS (NQNFS) are kernel resident, but make use of a few system daemons. The kernel implementation does not use an RPC library, handling the RPC request and reply messages directly in mbuf data areas. NFS interfaces to

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