1.\" Copyright (c) 1992, 1993, 1994, 1995 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)mount_nfs.8 8.3 (Berkeley) 3/29/95 29.\" $FreeBSD$ 30.\" 31.Dd February 11, 2008 32.Dt MOUNT_NFS 8 33.Os 34.Sh NAME 35.Nm mount_nfs 36.Nd mount NFS file systems 37.Sh SYNOPSIS 38.Nm 39.Op Fl 234bcdiLlNPsTU 40.Op Fl a Ar maxreadahead 41.Op Fl D Ar deadthresh 42.Op Fl g Ar maxgroups 43.Op Fl I Ar readdirsize 44.Op Fl o Ar options 45.Op Fl R Ar retrycnt 46.Op Fl r Ar readsize 47.Op Fl t Ar timeout 48.Op Fl w Ar writesize 49.Op Fl x Ar retrans 50.Ar rhost : Ns Ar path node 51.Sh DESCRIPTION 52The 53.Nm 54utility calls the 55.Xr nmount 2 56system call to prepare and graft a remote NFS file system 57.Pq Ar rhost : Ns Ar path 58on to the file system tree at the point 59.Ar node . 60This command is normally executed by 61.Xr mount 8 . 62It implements the mount protocol as described in RFC 1094, Appendix A and 63.%T "NFS: Network File System Version 3 Protocol Specification" , 64Appendix I. 65.Pp 66By default, 67.Nm 68keeps retrying until the mount succeeds. 69This behaviour is intended for file systems listed in 70.Xr fstab 5 71that are critical to the boot process. 72For non-critical file systems, the 73.Cm bg 74and 75.Cm retrycnt 76options provide mechanisms to prevent the boot process from hanging 77if the server is unavailable. 78.Pp 79If the server becomes unresponsive while an NFS file system is 80mounted, any new or outstanding file operations on that file system 81will hang uninterruptibly until the server comes back. 82To modify this default behaviour, see the 83.Cm intr 84and 85.Cm soft 86options. 87.Pp 88The options are: 89.Bl -tag -width indent 90.It Fl o 91Options are specified with a 92.Fl o 93flag followed by a comma separated string of options. 94See the 95.Xr mount 8 96man page for possible options and their meanings. 97The following NFS specific options are also available: 98.Bl -tag -width indent 99.It Cm acregmin Ns = Ns Aq Ar seconds 100.It Cm acregmax Ns = Ns Aq Ar seconds 101.It Cm acdirmin Ns = Ns Aq Ar seconds 102.It Cm acdirmax Ns = Ns Aq Ar seconds 103When attributes of files are cached, a timeout calculated to determine 104whether a given cache entry has expired. 105These four values determine the upper and lower bounds of the timeouts for 106.Dq directory 107attributes and 108.Dq regular 109(ie: everything else). 110The default values are 3 -> 60 seconds 111for regular files, and 30 -> 60 seconds for directories. 112The algorithm to calculate the timeout is based on the age of the file. 113The older the file, 114the longer the cache is considered valid, subject to the limits above. 115.It Cm bg 116If an initial attempt to contact the server fails, fork off a child to keep 117trying the mount in the background. 118Useful for 119.Xr fstab 5 , 120where the file system mount is not critical to multiuser operation. 121.It Cm deadthresh Ns = Ns Aq Ar value 122Set the 123.Dq "dead server threshold" 124to the specified number of round trip timeout intervals before a 125.Dq "server not responding" 126message is displayed. 127.It Cm dumbtimer 128Turn off the dynamic retransmit timeout estimator. 129This may be useful for UDP mounts that exhibit high retry rates, 130since it is possible that the dynamically estimated timeout interval is too 131short. 132.It Cm fg 133Same as not specifying 134.Cm bg . 135.It Cm hard 136Same as not specifying 137.Cm soft . 138.It Cm intr 139Make the mount interruptible, which implies that file system calls that 140are delayed due to an unresponsive server will fail with EINTR when a 141termination signal is posted for the process. 142.It Cm maxgroups Ns = Ns Aq Ar value 143Set the maximum size of the group list for the credentials to the 144specified value. 145This should be used for mounts on old servers that cannot handle a 146group list size of 16, as specified in RFC 1057. 147Try 8, if users in a lot of groups cannot get response from the mount 148point. 149.It Cm mntudp 150Force the mount protocol to use UDP transport, even for TCP NFS mounts. 151(Necessary for some old 152.Bx 153servers.) 154.It Cm nfsv2 155Use the NFS Version 2 protocol (the default is to try version 3 first 156then version 2). 157Note that NFS version 2 has a file size limit of 2 gigabytes. 158.It Cm nfsv3 159Use the NFS Version 3 protocol. 160.It Cm nfsv4 161Use the NFS Version 4 protocol. 162.It Cm noconn 163For UDP mount points, do not do a 164.Xr connect 2 . 165This must be used if the server does not reply to requests from the standard 166NFS port number 2049 or replies to requests using a different IP address 167(which can occur if the server is multi-homed). 168Setting the 169.Va vfs.nfs.nfs_ip_paranoia 170sysctl to 0 will make this option the default. 171.It Cm noinet4 , noinet6 172Disables 173.Dv AF_INET 174or 175.Dv AF_INET6 176connections. 177Useful for hosts that have 178both an A record and an AAAA record for the same name. 179.It Cm nolockd 180Do 181.Em not 182forward 183.Xr fcntl 2 184locks over the wire. 185All locks will be local and not seen by the server 186and likewise not seen by other NFS clients. 187This removes the need to run the 188.Xr rpcbind 8 189service and the 190.Xr rpc.statd 8 191and 192.Xr rpc.lockd 8 193servers on the client. 194Note that this option will only be honored when performing the 195initial mount, it will be silently ignored if used while updating 196the mount options. 197.It Cm noresvport 198Do 199.Em not 200use a reserved socket port number (see below). 201.It Cm port Ns = Ns Aq Ar port_number 202Use specified port number for NFS requests. 203The default is to query the portmapper for the NFS port. 204.It Cm rdirplus 205Used with NQNFS and NFSV3 to specify that the \fBReaddirPlus\fR RPC should 206be used. 207This option reduces RPC traffic for cases such as 208.Dq "ls -l" , 209but tends to flood the attribute and name caches with prefetched entries. 210Try this option and see whether performance improves or degrades. 211Probably 212most useful for client to server network interconnects with a large bandwidth 213times delay product. 214.It Cm readahead Ns = Ns Aq Ar value 215Set the read-ahead count to the specified value. 216This may be in the range of 0 - 4, and determines how many blocks 217will be read ahead when a large file is being read sequentially. 218Trying a value greater than 1 for this is suggested for 219mounts with a large bandwidth * delay product. 220.It Cm readdirsize Ns = Ns Aq Ar value 221Set the readdir read size to the specified value. 222The value should normally 223be a multiple of 224.Dv DIRBLKSIZ 225that is <= the read size for the mount. 226.It Cm resvport 227Use a reserved socket port number. 228This flag is obsolete, and only retained for compatibility reasons. 229Reserved port numbers are used by default now. 230(For the rare case where the client has a trusted root account 231but untrustworthy users and the network cables are in secure areas this does 232help, but for normal desktop clients this does not apply.) 233.It Cm retrans Ns = Ns Aq Ar value 234Set the retransmit timeout count for soft mounts to the specified value. 235.It Cm retrycnt Ns = Ns Aq Ar count 236Set the mount retry count to the specified value. 237The default is a retry count of zero, which means to keep retrying 238forever. 239There is a 60 second delay between each attempt. 240.It Cm rsize Ns = Ns Aq Ar value 241Set the read data size to the specified value. 242It should normally be a power of 2 greater than or equal to 1024. 243This should be used for UDP mounts when the 244.Dq "fragments dropped due to timeout" 245value is getting large while actively using a mount point. 246(Use 247.Xr netstat 1 248with the 249.Fl s 250option to see what the 251.Dq "fragments dropped due to timeout" 252value is.) 253.It Cm soft 254A soft mount, which implies that file system calls will fail 255after 256.Ar retrycnt 257round trip timeout intervals. 258.It Cm tcp 259Use TCP transport. 260This is the default option, as it provides for increased reliability on both 261LAN and WAN configurations compared to UDP. 262Some old NFS servers do not support this method; UDP mounts may be required 263for interoperability. 264.It Cm timeout Ns = Ns Aq Ar value 265Set the initial retransmit timeout to the specified value. 266May be useful for fine tuning UDP mounts over internetworks 267with high packet loss rates or an overloaded server. 268Try increasing the interval if 269.Xr nfsstat 1 270shows high retransmit rates while the file system is active or reducing the 271value if there is a low retransmit rate but long response delay observed. 272(Normally, the 273.Cm dumbtimer 274option should be specified when using this option to manually 275tune the timeout 276interval.) 277.It Cm udp 278Use UDP transport. 279.It Cm wsize Ns = Ns Aq Ar value 280Set the write data size to the specified value. 281Ditto the comments w.r.t.\& the 282.Cm rsize 283option, but using the 284.Dq "fragments dropped due to timeout" 285value on the server instead of the client. 286Note that both the 287.Cm rsize 288and 289.Cm wsize 290options should only be used as a last ditch effort at improving performance 291when mounting servers that do not support TCP mounts. 292.El 293.El 294.Sh COMPATIBILITY 295The following command line flags are equivalent to 296.Fl o 297named options and are supported for compatibility with older 298installations. 299.Bl -tag -width indent 300.It Fl 2 301Same as 302.Fl o Cm nfsv2 303.It Fl 3 304Same as 305.Fl o Cm nfsv3 306.It Fl 4 307Same as 308.Fl o Cm nfsv4 309.It Fl D 310Same as 311.Fl o Cm deadthresh 312.It Fl I 313Same as 314.Fl o Cm readdirsize Ns = Ns Aq Ar value 315.It Fl L 316Same as 317.Fl o Cm nolockd 318.It Fl N 319Same as 320.Fl o Cm noresvport 321.It Fl P 322Use a reserved socket port number. 323This flag is obsolete, and only retained for compatibility reasons. 324(For the rare case where the client has a trusted root account 325but untrustworthy users and the network cables are in secure areas this does 326help, but for normal desktop clients this does not apply.) 327.It Fl R 328Same as 329.Fl o Cm retrycnt Ns = Ns Aq Ar value 330.It Fl T 331Same as 332.Fl o Cm tcp 333.It Fl U 334Same as 335.Fl o Cm mntudp 336.It Fl a 337Same as 338.Fl o Cm readahead Ns = Ns Aq Ar value 339.It Fl b 340Same as 341.Fl o Cm bg 342.It Fl c 343Same as 344.Fl o Cm noconn 345.It Fl d 346Same as 347.Fl o Cm dumbtimer 348.It Fl g 349Same as 350.Fl o Cm maxgroups 351.It Fl i 352Same as 353.Fl o Cm intr 354.It Fl l 355Same as 356.Fl o Cm rdirplus 357.It Fl r 358Same as 359.Fl o Cm rsize Ns = Ns Aq Ar value 360.It Fl s 361Same as 362.Fl o Cm soft 363.It Fl t 364Same as 365.Fl o Cm retransmit Ns = Ns Aq Ar value 366.It Fl w 367Same as 368.Fl o Cm wsize Ns = Ns Aq Ar value 369.It Fl x 370Same as 371.Fl o Cm retrans Ns = Ns Aq Ar value 372.El 373.Sh SEE ALSO 374.Xr nmount 2 , 375.Xr unmount 2 , 376.Xr fstab 5 , 377.Xr mount 8 , 378.Xr nfsd 8 , 379.Xr nfsiod 8 , 380.Xr showmount 8 381