NFS(7P-SysV)        RISC/os Reference Manual         NFS(7P-SysV)



NAME
     nfs, NFS - network file system

CONFIG
     options NFS

DESCRIPTION
     The Network File System, or NFS, allows a client workstation
     to perform transparent file access over the network.  Using
     it, a client workstation 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 Network File System operates in a stateless fashion
     using remote procedure (RPC) calls built on top of external
     data representation (XDR) protocol.  These protocols are
     documented in the chapter "NFS User's Guide" in the System
     Administrator's Guide. The RPC protocol provides for version
     and authentication parameters 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(2)
     system call, which requests a file handle for the filesystem
     itself.  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 chapter "NFS User's Guide" in the System
     Administrator's Guide.




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NFS(7P-SysV)        RISC/os Reference Manual         NFS(7P-SysV)



ERRORS
     Generally physical disk I/O errors detected at the server
     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.  It also
     means the client process requesting the I/O will block and
     remain insensitive to signals, sleeping inside the kernel at
     PRIBIO.

FILES
     /etc/exports

SEE ALSO
     mount(1M), nfsd(1M).
     mount(2), exports(4), fstab(4), mntent(4) in the
     Programmer's Reference Manual.
     The chapter "NFS User's Guide" in the System Administrator's
     Guide.

ORIGIN
     Sun Microsystems





























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