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A bstvactThis paper presents an architecture for a file service capable of supporting a very large number of users and providing for each user a lifetime involvement with the file service, while giving the appearance of a single homogeneous system. The architecture is based on the provision of an independent name space for each user and the use of hints for name resolution.Concern about efficient implementation of the architecture leads to the support of file caching and the use of server callbacks to aid in maintaining cache consistency. Updatein-place semantics are provided for those applications that require direct access to localized parts of files, but particularly efficient cache validation strategies encourage the use of immutable files. All file service metadata are updated in atomic and recoverable ways using write-ahead logging. The file service also supports user-level distributed atomic actions based on a two-phase commit synchronization protocol.The file service supports user and resource reassignments in a location-independent way by employing the system's user location mechanism during file name resolution when hints are invalid. File sharing information remains valid even when participants migrate.

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