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nfs(5) - nfs, nfs - nfs fstab format and options - man 5 nfs

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NFS(5)                     Linux Programmer's Manual                    NFS(5)



NAME
       nfs - nfs fstab format and options

SYNOPSIS
       /etc/fstab

DESCRIPTION
       The  fstab  file(1,n)  contains information about which filesystems to mount(2,8)
       where and with what options.  For NFS mounts, it  contains  the  server
       name  and  exported server directory to mount(2,8) from, the local directory
       that is the mount(2,8) point, and the NFS specific options that control  the
       way the filesystem is mounted.

       Here is an example from an /etc/fstab file(1,n) from an NFS mount.

       server:/usr/local/pub    /pub   nfs    rsize=8192,wsize=8192,timeo=14,intr

   Options
       rsize=n        The  number of bytes NFS uses when reading files from an
                      NFS server.  The default value is dependent on the  ker-
                      nel,  currently  1024  bytes.   (However,  throughput is
                      improved greatly by asking for rsize=8192.)

       wsize=n        The number of bytes NFS uses when writing  files  to  an
                      NFS  server.  The default value is dependent on the ker-
                      nel, currently  1024  bytes.   (However,  throughput  is
                      improved greatly by asking for wsize=8192.)

       timeo=n        The value in(1,8) tenths of a second before sending the first
                      retransmission after an RPC timeout.  The default  value
                      is  7  tenths of a second.  After the first timeout(1,3x,3x cbreak), the
                      timeout(1,3x,3x cbreak) is doubled after each successive timeout(1,3x,3x cbreak) until a
                      maximum  timeout(1,3x,3x cbreak)  of 60 seconds is reached or the enough
                      retransmissions have occured to cause a  major  timeout.
                      Then,  if(3,n) the filesystem is hard mounted, each new time-
                      out(1,3x,3x cbreak) cascade restarts at twice the initial value  of  the
                      previous cascade, again doubling at each retransmission.
                      The maximum timeout(1,3x,3x cbreak) is always 60 seconds.  Better  over-
                      all  performance may be achieved by increasing the time-
                      out(1,3x,3x cbreak) when mounting on a busy network, to a  slow  server,
                      or through several routers or gateways.

       retrans=n      The  number  of  minor timeouts and retransmissions that
                      must occur before a major timeout(1,3x,3x cbreak) occurs.   The  default
                      is  3  timeouts.   When a major timeout(1,3x,3x cbreak) occurs, the file(1,n)
                      operation is either aborted or a "server not responding"
                      message is printed on the console.

       acregmin=n     The minimum time(1,2,n) in(1,8) seconds that attributes of a regular
                      file(1,n) should be cached before requesting  fresh  informa-
                      tion from a server.  The default is 3 seconds.

       acregmax=n     The maximum time(1,2,n) in(1,8) seconds that attributes of a regular
                      file(1,n) can be cached before requesting  fresh  information
                      from a server.  The default is 60 seconds.

       acdirmin=n     The  minimum time(1,2,n) in(1,8) seconds that attributes of a direc-
                      tory should be cached before requesting  fresh  informa-
                      tion from a server.  The default is 30 seconds.

       acdirmax=n     The  maximum time(1,2,n) in(1,8) seconds that attributes of a direc-
                      tory can be cached before requesting  fresh  information
                      from a server.  The default is 60 seconds.

       actimeo=n      Using  actimeo sets all of acregmin, acregmax, acdirmin,
                      and acdirmax to the same value.   There  is  no  default
                      value.

       retry=n        The number of minutes to retry an NFS mount(2,8) operation in(1,8)
                      the foreground or  background  before  giving  up.   The
                      default  value  is  10000  minutes, which is roughly one
                      week.

       namlen=n       When an NFS server does not support version(1,3,5) two  of  the
                      RPC  mount(2,8)  protocol, this option can be used to specify
                      the maximum length of a filename that  is  supported  on
                      the  remote  filesystem.   This  is  used to support the
                      POSIX pathconf functions.  The default  is  255  charac-
                      ters.

       port=n         The  numeric  value  of  the  port to connect to the NFS
                      server on.  If the port number is 0 (the  default)  then
                      query  the  remote host(1,5)'s portmapper for the port number
                      to use.  If the remote host(1,5)'s NFS daemon is  not  regis-
                      tered  with its portmapper, the standard NFS port number
                      2049 is used instead.

       mountport=n    The numeric value of the mountd port.

       mounthost=name The name of the host(1,5) running mountd .

       mountprog=n    Use an alternate RPC program number to contact the mount(2,8)
                      daemon  on  the  remote host.  This option is useful for
                      hosts that can run multiple NFS  servers.   The  default
                      value  is  100005 which is the standard RPC mount(2,8) daemon
                      program number.

       mountvers=n    Use an alternate RPC version(1,3,5) number to contact the mount(2,8)
                      daemon  on  the  remote host.  This option is useful for
                      hosts that can run multiple NFS  servers.   The  default
                      value is version(1,3,5) 1.

       nfsprog=n      Use  an  alternate RPC program number to contact the NFS
                      daemon on the remote host.  This option  is  useful  for
                      hosts  that  can  run multiple NFS servers.  The default
                      value is 100003 which is the  standard  RPC  NFS  daemon
                      program number.

       nfsvers=n      Use  an  alternate RPC version(1,3,5) number to contact the NFS
                      daemon on the remote host.  This option  is  useful  for
                      hosts  that  can  run multiple NFS servers.  The default
                      value is version(1,3,5) 2.

       nolock         Disable NFS locking. Do not start lockd.  This has to be
                      used  with some old NFS servers that don't support lock-
                      ing.

       bg             If the first NFS mount(2,8)  attempt  times  out,  retry  the
                      mount(2,8)  in(1,8)  the  background.   After a mount(2,8) operation is
                      backgrounded, all subsequent  mounts  on  the  same  NFS
                      server  will  be backgrounded immediately, without first
                      attempting the mount.  A missing mount(2,8) point is  treated
                      as a timeout(1,3x,3x cbreak), to allow for nested NFS mounts.

       fg             If  the  first  NFS  mount(2,8)  attempt times out, retry the
                      mount(2,8) in(1,8) the foreground.  This is the complement of  the
                      bg option, and also the default behavior.

       soft           If an NFS file(1,n) operation has a major timeout(1,3x,3x cbreak) then report
                      an I/O error(8,n) to the calling program.  The default is  to
                      continue retrying NFS file(1,n) operations indefinitely.

       hard           If an NFS file(1,n) operation has a major timeout(1,3x,3x cbreak) then report
                      "server not responding"  on  the  console(4,n)  and  continue
                      retrying indefinitely.  This is the default.

       intr           If  an  NFS file(1,n) operation has a major timeout(1,3x,3x cbreak) and it is
                      hard mounted, then allow signals to  interupt  the  file(1,n)
                      operation  and  cause  it to return EINTR to the calling
                      program.  The default is to not allow file(1,n) operations to
                      be interrupted.

       posix          Mount  the  NFS  filesystem using POSIX semantics.  This
                      allows an NFS filesystem to properly support  the  POSIX
                      pathconf  command  by  querying the mount(2,8) server for the
                      maximum length of a filename.  To do  this,  the  remote
                      host(1,5) must support version(1,3,5) two of the RPC mount(2,8) protocol.
                      Many NFS servers support only version(1,3,5) one.

       nocto          Suppress the retrieval of new attributes when creating a
                      file.

       noac           Disable  all  forms of attribute caching entirely.  This
                      extracts a server performance penalty but it allows  two
                      different  NFS  clients  to  get reasonable good results
                      when  both  clients  are  actively  writing  to   common
                      filesystem on the server.

       tcp            Mount  the NFS filesystem using the TCP protocol instead
                      of the default UDP protocol.  Many NFS servers only sup-
                      port UDP.

       udp            Mount  the  NFS filesystem using the UDP protocol.  This
                      is the default.

       All of the non-value options have corresponding  nooption  forms.   For
       example, nointr means don't allow file(1,n) operations to be interrupted.

FILES
       /etc/fstab

SEE ALSO
       fstab(5), mount(2,8)(8), umount(8), exports(5)

AUTHOR
       "Rick Sladkey" <jrs@world.std.com>

BUGS
       The  posix,  and  nocto  options  are parsed by mount(2,8) but currently are
       silently ignored.

       The tcp and namlen options are implemented but are not  currently  sup-
       ported by the Linux kernel.

       The  umount  command should notify the server when an NFS filesystem is
       unmounted.



Linux 0.99                     20 November 1993                         NFS(5)

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