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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	 contains information about which filesystems to mount
       where and with what options.  For NFS mounts, it	 contains  the	server
       name  and  exported server directory to mount from, the local directory
       that is the mount point,	and the	NFS specific options that control  the
       way the filesystem is mounted.

       Here is an example from an /etc/fstab file 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 im-
		      proved 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  im-
		      proved greatly by	asking for wsize=8192.)

       timeo=n	      The value	in 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, the
		      timeout is doubled after each successive timeout until a
		      maximum  timeout	of 60 seconds is reached or the	enough
		      retransmissions have occured to cause a  major  timeout.
		      Then,  if	the filesystem is hard mounted,	each new time-
		      out cascade restarts at twice the	initial	value  of  the
		      previous cascade,	again doubling at each retransmission.
		      The maximum timeout is always 60 seconds.	 Better	 over-
		      all  performance may be achieved by increasing the time-
		      out 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	occurs.	  The  default
		      is  3  timeouts.	 When a	major timeout occurs, the file
		      operation	is either aborted or a "server not responding"
		      message is printed on the	console.

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

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

       acdirmin=n     The  minimum time	in 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	in 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 operation in
		      the foreground or	background before giving up.  The  de-
		      fault value is 10000 minutes, which is roughly one week.

       namlen=n	      When  an	NFS server does	not support version two	of the
		      RPC mount	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's portmapper for the  port	number
		      to  use.	 If the	remote host'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 running mountd .

       mountprog=n    Use an alternate RPC program number to contact the mount
		      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	daemon
		      program number.

       mountvers=n    Use an alternate RPC version number to contact the mount
		      daemon on	the remote host.  This option  is  useful  for
		      hosts  that  can	run multiple NFS servers.  The default
		      value is version 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 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 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  attempt times	out, retry the
		      mount in the background.	After  a  mount	 operation  is
		      backgrounded,  all  subsequent  mounts  on  the same NFS
		      server will be backgrounded immediately,	without	 first
		      attempting  the mount.  A	missing	mount point is treated
		      as a timeout, to allow for nested	NFS mounts.

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

       soft	      If an NFS	file operation has a major timeout then	report
		      an  I/O error to the calling program.  The default is to
		      continue retrying	NFS file operations indefinitely.

       hard	      If an NFS	file operation has a major timeout then	report
		      "server  not  responding"	 on  the  console and continue
		      retrying indefinitely.  This is the default.

       intr	      If an NFS	file operation has a major timeout and	it  is
		      hard  mounted,  then  allow signals to interupt the file
		      operation	and cause it to	return EINTR  to  the  calling
		      program.	The default is to not allow file 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  server  for  the
		      maximum  length  of  a filename.	To do this, the	remote
		      host must	support	version	two of the RPC mount protocol.
		      Many NFS servers support only version 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 operations to be interrupted.

FILES
       /etc/fstab

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

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

BUGS
       The posix, and nocto options are	parsed	by  mount  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)

NAME | SYNOPSIS | DESCRIPTION | FILES | SEE ALSO | AUTHOR | BUGS

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