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MOUNT_NFS(8)		FreeBSD	System Manager's Manual		  MOUNT_NFS(8)

NAME
     mount_nfs -- mount	NFS file systems

SYNOPSIS
     mount_nfs [-23bcdiLlNPsTU]	[-a maxreadahead] [-D deadthresh]
	       [-g maxgroups] [-I readdirsize] [-o options] [-R	retrycnt]
	       [-r readsize] [-t timeout] [-w writesize] [-x retrans]
	       rhost:path node

DESCRIPTION
     The mount_nfs utility calls the nmount(2) system call to prepare and
     graft a remote NFS	file system (rhost:path) on to the file	system tree at
     the point node.  This command is normally executed	by mount(8).  It
     implements	the mount protocol as described	in RFC 1094, Appendix A	and
     NFS: Network File System Version 3	Protocol Specification,	Appendix I.

     By	default, mount_nfs keeps retrying until	the mount succeeds.  This be-
     haviour is	intended for file systems listed in fstab(5) that are critical
     to	the boot process.  For non-critical file systems, the -b and -R	flags
     provide mechanisms	to prevent the boot process from hanging if the	server
     is	unavailable.

     If	the server becomes unresponsive	while an NFS file system is mounted,
     any new or	outstanding file operations on that file system	will hang
     uninterruptibly until the server comes back.  To modify this default be-
     haviour, see the -i and -s	flags.

     The options are:

     -2	     Use the NFS Version 2 protocol (the default is to try version 3
	     first then	version	2).  Note that NFS version 2 has a file	size
	     limit of 2	gigabytes.

     -3	     Use the NFS Version 3 protocol.

     -4	     Use the NFS Version 4 protocol.

     -D	     Set the ``dead server threshold'' to the specified	number of
	     round trip	timeout	intervals before a ``server not	responding''
	     message is	displayed.

     -I	     Set the readdir read size to the specified	value.	The value
	     should normally be	a multiple of DIRBLKSIZ	that is	<= the read
	     size for the mount.

     -L	     Do	not forward fcntl(2) locks over	the wire.  All locks will be
	     local and not seen	by the server and likewise not seen by other
	     NFS clients.  This	removes	the need to run	the rpcbind(8) service
	     and the rpc.statd(8) and rpc.lockd(8) servers on the client.
	     Note that this option will	only be	honored	when performing	the
	     initial mount, it will be silently	ignored	if used	while updating
	     the mount options.

     -N	     Do	not use	a reserved socket port number (see below).

     -P	     Use a reserved socket port	number.	 This flag is obsolete,	and
	     only retained for compatibility reasons.  Reserved	port numbers
	     are used by default now.  (For the	rare case where	the client has
	     a trusted root account but	untrustworthy users and	the network
	     cables are	in secure areas	this does help,	but for	normal desktop
	     clients this does not apply.)

     -R	     Set the mount retry count to the specified	value.	The default is
	     a retry count of zero, which means	to keep	retrying forever.
	     There is a	60 second delay	between	each attempt.

     -T	     Use TCP transport instead of UDP.	This is	recommended for
	     servers that are not on the same LAN cable	as the client.	Not
	     all NFS servers support this method, especially older ones; cau-
	     tion should be observed in	these cases.

     -U	     Force the mount protocol to use UDP transport, even for TCP NFS
	     mounts.  (Necessary for some old BSD servers.)

     -a	     Set the read-ahead	count to the specified value.  This may	be in
	     the range of 0 - 4, and determines	how many blocks	will be	read
	     ahead when	a large	file is	being read sequentially.  Trying a
	     value greater than	1 for this is suggested	for mounts with	a
	     large bandwidth * delay product.

     -b	     If	an initial attempt to contact the server fails,	fork off a
	     child to keep trying the mount in the background.	Useful for
	     fstab(5), where the file system mount is not critical to multi-
	     user operation.

     -c	     For UDP mount points, do not do a connect(2).  This must be used
	     if	the server does	not reply to requests from the standard	NFS
	     port number 2049 or replies to requests using a different IP
	     address (which can	occur if the server is multi-homed).  Setting
	     the vfs.nfs.nfs_ip_paranoia sysctl	to 0 will make this option the
	     default.

     -d	     Turn off the dynamic retransmit timeout estimator.	 This may be
	     useful for	UDP mounts that	exhibit	high retry rates, since	it is
	     possible that the dynamically estimated timeout interval is too
	     short.

     -g	     Set the maximum size of the group list for	the credentials	to the
	     specified value.  This should be used for mounts on old servers
	     that cannot handle	a group	list size of 16, as specified in RFC
	     1057.  Try	8, if users in a lot of	groups cannot get response
	     from the mount point.

     -i	     Make the mount interruptible, which implies that file system
	     calls that	are delayed due	to an unresponsive server will fail
	     with EINTR	when a termination signal is posted for	the process.

     -l	     Used with NQNFS and NFSV3 to specify that the ReaddirPlus RPC
	     should be used.  This option reduces RPC traffic for cases	such
	     as	``ls -l'', but tends to	flood the attribute and	name caches
	     with prefetched entries.  Try this	option and see whether perfor-
	     mance improves or degrades.  Probably most	useful for client to
	     server network interconnects with a large bandwidth times delay
	     product.

     -o	     Options are specified with	a -o flag followed by a	comma sepa-
	     rated string of options.  See the mount(8)	man page for possible
	     options and their meanings.  The following	NFS specific options
	     are also available:

	     port=<port_number>
		     Use specified port	number for NFS requests.  The default
		     is	to query the portmapper	for the	NFS port.

	     acregmin=<seconds>

	     acregmax=<seconds>

	     acdirmin=<seconds>

	     acdirmax=<seconds>
		     When attributes of	files are cached, a timeout calculated
		     to	determine whether a given cache	entry has expired.
		     These four	values determine the upper and lower bounds of
		     the timeouts for ``directory'' attributes and ``regular''
		     (ie: everything else).  The default values	are 3 -> 60
		     seconds for regular files,	and 30 -> 60 seconds for
		     directories.  The algorithm to calculate the timeout is
		     based on the age of the file.  The	older the file,	the
		     longer the	cache is considered valid, subject to the lim-
		     its above.

	     noinet4, noinet6
		     Disables AF_INET or AF_INET6 connections.	Useful for
		     hosts that	have both an A record and an AAAA record for
		     the same name.

	     Historic -o Options

	     Use of these options is deprecated, they are only mentioned here
	     for compatibility with historic versions of mount_nfs.

	     bg		Same as	-b.

	     fg		Same as	not specifying -b.

	     conn	Same as	not specifying -c.

	     dumbtimer	Same as	-d.

	     intr	Same as	-i.

	     lockd	Same as	not specifying -L.

	     nfsv2	Same as	-2.

	     nfsv3	Same as	-3.

	     rdirplus	Same as	-l.

	     mntudp	Same as	-U.

	     resvport	Same as	-P.

	     soft	Same as	-s.

	     hard	Same as	not specifying -s.

	     tcp	Same as	-T.

     -r	     Set the read data size to the specified value.  It	should nor-
	     mally be a	power of 2 greater than	or equal to 1024.  This	should
	     be	used for UDP mounts when the ``fragments dropped due to
	     timeout'' value is	getting	large while actively using a mount
	     point.  (Use netstat(1) with the -s option	to see what the
	     ``fragments dropped due to	timeout'' value	is.)  See the -w
	     option as well.

     -s	     A soft mount, which implies that file system calls	will fail
	     after retrycnt round trip timeout intervals.

     -t	     Set the initial retransmit	timeout	to the specified value.	 May
	     be	useful for fine	tuning UDP mounts over internetworks with high
	     packet loss rates or an overloaded	server.	 Try increasing	the
	     interval if nfsstat(1) shows high retransmit rates	while the file
	     system is active or reducing the value if there is	a low retrans-
	     mit rate but long response	delay observed.	 (Normally, the	-d
	     option should be specified	when using this	option to manually
	     tune the timeout interval.)

     -w	     Set the write data	size to	the specified value.  Ditto the	com-
	     ments w.r.t. the -r option, but using the ``fragments dropped due
	     to	timeout'' value	on the server instead of the client.  Note
	     that both the -r and -w options should only be used as a last
	     ditch effort at improving performance when	mounting servers that
	     do	not support TCP	mounts.

     -x	     Set the retransmit	timeout	count for soft mounts to the specified
	     value.

SEE ALSO
     nmount(2),	unmount(2), fstab(5), mount(8),	nfsd(8), nfsiod(8),
     showmount(8)

FreeBSD	10.1		       December	25, 2005		  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO

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