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.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)mount_nfs.8 8.3 (Berkeley) 3/29/95 33.\" 34.\" $Id: mount_nfs.8,v 1.7 1997/02/22 14:32:47 peter Exp $ 35.\"" 36.Dd March 29, 1995 37.Dt MOUNT_NFS 8 38.Os BSD 4.4 39.Sh NAME 40.Nm mount_nfs 41.Nd mount nfs file systems 42.Sh SYNOPSIS 43.Nm mount_nfs 44.Op Fl 3KPTUbcdilqs 45.Op Fl D Ar deadthresh 46.Op Fl I Ar readdirsize 47.Op Fl L Ar leaseterm 48.Op Fl R Ar retrycnt 49.Op Fl a Ar maxreadahead 50.Op Fl g Ar maxgroups 51.Op Fl m Ar realm 52.Op Fl o Ar options 53.Op Fl r Ar readsize 54.Op Fl t Ar timeout 55.Op Fl w Ar writesize 56.Op Fl x Ar retrans 57.Ar rhost:path node 58.Sh DESCRIPTION 59The 60.Nm mount_nfs 61command 62calls the 63.Xr mount 2 64system call to prepare and graft a remote nfs file system (rhost:path) 65on to the file system tree at the point 66.Ar node. 67This command is normally executed by 68.Xr mount 8 . 69It implements the mount protocol as described in RFC 1094, Appendix A and 70.%T "NFS: Network File System Version 3 Protocol Specification" , 71Appendix I. 72.Pp 73The options are: 74.Bl -tag -width indent 75.It Fl 3 76Use the NFS Version 3 protocol (Version 2 is the default). 77.It Fl D 78Used with NQNFS to set the 79.Dq "dead server threshold" 80to the specified number of round trip timeout intervals. 81After a 82.Dq "dead server threshold" 83of retransmit timeouts, 84cached data for the unresponsive server is assumed to still be valid. 85Values may be set in the range of 1 - 9, with 9 referring to an 86.Dq "infinite dead threshold" 87(i.e. never assume cached data still valid). 88This option is not generally recommended and is really an experimental 89feature. 90.It Fl I 91Set the readdir read size to the specified value. The value should normally 92be a multiple of DIRBLKSIZ that is <= the read size for the mount. 93.It Fl K 94Pass Kerberos authenticators to the server for client-to-server 95user-credential mapping. 96This requires that the kernel be built with the NFSKERB option. 97(Refer to the INTERNET-DRAFT titled 98.%T "Authentication Mechanisms for ONC RPC" , 99for more information.) 100.It Fl L 101Used with NQNFS to set the lease term to the specified number of seconds. 102Only use this argument for mounts with a large round trip delay. 103Values are normally in the 10-30 second range. 104.It Fl P 105Use a reserved socket port number. 106This is useful for mounting servers that require clients to use a 107reserved port number on the mistaken belief that this makes NFS 108more secure. (For the rare case where the client has a trusted root account 109but untrustworthy users and the network cables are in secure areas this does 110help, but for normal desktop clients this does not apply.) 111.It Fl R 112Set the retry count for doing the mount to the specified value. 113.It Fl T 114Use TCP transport instead of UDP. 115This is recommended for servers that are not on the same LAN cable as 116the client. 117(NB: This is NOT supported by most non-BSD servers.) 118.It Fl U 119Force the mount protocol to use UDP transport, even for TCP NFS mounts. 120(Necessary for some old BSD servers.) 121.It Fl a 122Set the read-ahead count to the specified value. 123This may be in the range of 0 - 4, and determines how many blocks 124will be read ahead when a large file is being read sequentially. 125Trying a value greater than 1 for this is suggested for 126mounts with a large bandwidth * delay product. 127.It Fl b 128If an initial attempt to contact the server fails, fork off a child to keep 129trying the mount in the background. 130Useful for 131.Xr fstab 5 , 132where the filesystem mount is not critical to multiuser operation. 133.It Fl c 134For UDP mount points, do not do a 135.Xr connect 2 . 136This must be used for servers that do not reply to requests from the 137standard NFS port number 2049. 138.It Fl d 139Turn off the dynamic retransmit timeout estimator. 140This may be useful for UDP mounts that exhibit high retry rates, 141since it is possible that the dynamically estimated timeout interval is too 142short. 143.It Fl g 144Set the maximum size of the group list for the credentials to the 145specified value. 146This should be used for mounts on old servers that cannot handle a 147group list size of 16, as specified in RFC 1057. 148Try 8, if users in a lot of groups cannot get response from the mount 149point. 150.It Fl i 151Make the mount interruptible, which implies that file system calls that 152are delayed due to an unresponsive server will fail with EINTR when a 153termination signal is posted for the process. 154.It Fl l 155Used with NQNFS and NFSV3 to specify that the \fBReaddirPlus\fR RPC should 156be used. 157This option reduces RPC traffic for cases such as 158.Dq "ls -l" , 159but tends to flood the attribute and name caches with prefetched entries. 160Try this option and see whether performance improves or degrades. Probably 161most useful for client to server network interconnects with a large bandwidth 162times delay product. 163.It Fl m 164Set the Kerberos realm to the string argument. 165Used with the 166.Fl K 167option for mounts to other realms. 168.It Fl o 169Options are specified with a 170.Fl o 171flag followed by a comma separated string of options. 172See the 173.Xr mount 8 174man page for possible options and their meanings. 175The following NFS specific option is also available: 176.Bl -tag -width indent 177.It port=<port_number> 178Use specified port number for NFS requests. 179The default is to query the portmapper for the NFS port. 180.El 181.Pp 182.Bl -tag -width "dumbtimerXX" 183\fBHistoric \&-o options\fR 184.Pp 185Use of these options is deprecated, they are only mentioned here for 186compatibility with historic versions of 187.Nm mount_nfs . 188.It bg 189Same as 190.Fl b . 191.It conn 192Same as 193.Fl c . 194.It dumbtimer 195Same as 196.Fl d . 197.It intr 198Same as 199.Fl i . 200.It kerb 201Same as 202.Fl K . 203.It nfsv3 204Same as 205.Fl 3 . 206.It rdirplus 207Same as 208.Fl l . 209.It mntudp 210Same as 211.Fl U . 212.It resvport 213Same as 214.Fl P . 215.It seqpacket 216Same as 217.Fl p . 218.It nqnfs 219Same as 220.Fl q . 221.It soft 222Same as 223.Fl s . 224.It tcp 225Same as 226.Fl T. 227.El 228.It Fl q 229Use the leasing extensions to the NFS Version 3 protocol 230to maintain cache consistency. 231This protocol Version 2, referred to as Not Quite Nfs (NQNFS), 232is only supported by this updated release of NFS code. 233(It is not backwards compatible with the release of NQNFS that went out on 2344.4BSD-Lite. To interoperate with a 4.4BSD-Lite NFS system you will have to 235avoid this option until you have had an opportunity to upgrade the NFS code 236on all your 4.4BSD-Lite based systems.) 237.It Fl r 238Set the read data size to the specified value. 239It should normally be a power of 2 greater than or equal to 1024. 240This should be used for UDP mounts when the 241.Dq "fragments dropped due to timeout" 242value is getting large while actively using a mount point. 243(Use 244.Xr netstat 1 245with the 246.Fl s 247option to see what the 248.Dq "fragments dropped due to timeout" 249value is.) 250See the 251.Fl w 252option as well. 253.It Fl s 254A soft mount, which implies that file system calls will fail 255after \fBRetry\fR round trip timeout intervals. 256.It Fl t 257Set the initial retransmit timeout to the specified value. 258May be useful for fine tuning UDP mounts over internetworks 259with high packet loss rates or an overloaded server. 260Try increasing the interval if 261.Xr nfsstat 1 262shows high retransmit rates while the file system is active or reducing the 263value if there is a low retransmit rate but long response delay observed. 264(Normally, the -d option should be specified when using this option to manually 265tune the timeout 266interval.) 267.It Fl w 268Set the write data size to the specified value. 269Ditto the comments w.r.t. the 270.Fl r 271option, but using the 272.Dq "fragments dropped due to timeout" 273value on the server instead of the client. 274Note that both the 275.Fl r 276and 277.Fl w 278options should only be used as a last ditch effort at improving performance 279when mounting servers that do not support TCP mounts. 280.It Fl x 281Set the retransmit timeout count for soft mounts to the specified value. 282.El 283.Sh SEE ALSO 284.Xr mount 2 , 285.Xr unmount 2 , 286.Xr fstab 5 , 287.Xr mount 8 288.Sh BUGS 289Due to the way that Sun RPC is implemented on top of UDP (unreliable datagram) 290transport, tuning such mounts is really a black art that can only be expected 291to have limited success. 292For clients mounting servers that are not on the same 293LAN cable or that tend to be overloaded, 294TCP transport is strongly recommended, 295but unfortunately this is restricted to mostly 4.4BSD servers. 296