nfs(4P)                        NFS                        nfs(4P)



NAME
     nfs, NFS - network file system

SYNOPSIS
     options NFS

DESCRIPTION
     The Network File System, or NFS, allows a client system to
     perform transparent file access over the network.  Using it,
     a client system can operate on files that reside on a
     variety of servers, server architectures and across a
     variety of operating systems.  Client file access calls are
     converted to NFS protocol requests, and are sent to the
     server system over the network.  The server receives the
     request, performs the actual file system operation, and
     sends a response back to the client.

     The Nework File System operates in a stateless fashion using
     remote procedure (RPC) calls built on top of external data
     representation (XDR) protocol.  These protocols are docu-
     mented in the CX/UX Network File System (NFS) manual.  The
     RPC protocol provides for version and authentication parame-
     ters to be exchanged for security over the network.

     A server can grant access to a specific filesystem to cer-
     tain clients by adding an entry for that filesystem to the
     server's /etc/exports file.

     A client gains access to that filesystem with the mount(1M)
     utility.  Once the filesystem is mounted by the client, the
     server issues a file handle to the client for each file (or
     directory) the client accesses.  If the file is somehow
     removed on the server side, the file handle becomes stale
     (dissociated with a known file).

     A server may also be a client with respect to filesystems it
     has mounted over the network, but its clients cannot gain
     access to those filesystems.  Instead, the client must mount
     a filesystem directly from the server on which it resides.

     The user ID and group ID mappings must be the same between
     client and server.  However, the server maps uid 0 (the
     super-user) to uid -2 before performing access checks for a
     client.  This inhibits super-user privileges on remote
     filesystems.

     NFS-related routines and structure definitions are described
     in the Network File System Protocol Specification in the
     CX/UX Network File System (NFS) manual.

ERRORS
     Generally physical disk I/O errors detected at the server



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nfs(4P)                        NFS                        nfs(4P)



     are returned to the client for action.  If the server is
     down or inaccessable, the client will see the console mes-
     sage:
          NFS:  file server not responding: still trying.
     The client continues (forever) to resend the request until
     it receives an acknowledgement from the server.  This means
     the server can crash or power down, and come back up,
     without any special action required by the client.

SEE ALSO
     exports(4), fstab(4), mntent(4), mount(1M), nfsd(1M)












































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