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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 8.2 (Berkeley) 3/27/94 33.\" 34.Dd March 27, 1994 35.Dt MOUNT_NFS 8 36.Os BSD 4.4 37.Sh NAME 38.Nm mount_nfs 39.Nd mount nfs file systems 40.Sh SYNOPSIS 41.Nm mount_nfs 42.Op Fl KMPTbcdiklqs 43.Op Fl D Ar deadthresh 44.Op Fl L Ar leaseterm 45.Op Fl R Ar retrycnt 46.Op Fl a Ar maxreadahead 47.Op Fl g Ar maxgroups 48.Op Fl m Ar realm 49.Op Fl o Ar options 50.Op Fl r Ar readsize 51.Op Fl t Ar timeout 52.Op Fl w Ar writesize 53.Op Fl x Ar retrans 54.Ar rhost:path node 55.Sh DESCRIPTION 56The 57.Nm mount_nfs 58command 59calls the 60.Xr mount 2 61system call to prepare and graft a remote nfs file system (rhost:path) 62on to the file system tree at the point 63.Ar node. 64This command is normally executed by 65.Xr mount 8 . 66It implements the mount protocol as described in RFC 1094, Appendix A. 67.Pp 68The options are: 69.Bl -tag -width indent 70.It Fl D 71Used with NQNFS to set the 72.Dq "dead server threshold" 73to the specified number of round trip timeout intervals. 74After a 75.Dq "dead server threshold" 76of retransmit timeouts, 77cached data for the unresponsive server is assumed to still be valid. 78Values may be set in the range of 1 - 9, with 9 referring to an 79.Dq "infinite dead threshold" 80(i.e. never assume cached data still valid). 81This option is not generally recommended and is really an experimental 82feature. 83.It Fl K 84Pass Kerberos authenticators to the server for client-to-server 85user-credential mapping. 86This may only be used over TCP mounts between 4.4BSD clients and servers. 87.It Fl L 88Used with NQNFS to set the lease term to the specified number of seconds. 89Only use this argument for mounts with a large round trip delay. 90Values are normally in the 10-30 second range. 91.It Fl M 92Assume that other clients are not writing a file concurrently with this client. 93This implements a slightly less strict consistency criteria than 4.3BSD-Reno 94did, that is more in line with most commercial client implementations. 95This is recommended for servers that do not support leasing. 96.It Fl P 97Use a reserved socket port number. 98This is useful for mounting servers that require clients to use a 99reserved port number. 100.It Fl R 101Set the retry count for doing the mount to the specified value. 102.It Fl T 103Use TCP transport instead of UDP. 104This is recommended for servers that are not on the same LAN cable as 105the client. 106(NB: This is NOT supported by most non-BSD servers.) 107.It Fl a 108Set the read-ahead count to the specified value. 109This may be in the range of 0 - 4, and determines how many blocks 110will be read ahead when a large file is being read sequentially. 111This is recommended for mounts with a large bandwidth * delay product. 112.It Fl b 113If an initial attempt to contact the server fails, fork off a child to keep 114trying the mount in the background. 115Useful for 116.Xr fstab 5 , 117where the filesystem mount is not critical to multiuser operation. 118.It Fl c 119For UDP mount points, do not do a 120.Xr connect 2 . 121This must be used for servers that do not reply to requests from the 122standard port number. 123.It Fl d 124Do not estimate retransmit timeout dynamically. 125This may be useful for UDP mounts that exhibit high retry rates. 126.It Fl g 127Set the maximum size of the group list for the credentials to the 128specified value. 129This should be used for mounts on old servers that cannot handle a 130group list size of 16, as specified in RFC 1057. 131Try 8, if users in a lot of groups cannot get response from the mount 132point. 133.It Fl i 134Make the mount interruptible, which implies that file system calls that 135are delayed due to an unresponsive server will fail with EINTR when a 136termination signal is posted for the process. 137.It Fl k 138Used with NQNFS to specify 139.Dq get a lease 140for the file name being looked up. 141This is recommended unless the server is complaining about excessive 142lease load. 143.It Fl l 144Used with NQNFS to specify that the \fBReaddir_and_Lookup\fR RPC should 145be used. 146This option reduces RPC traffic for cases such as 147.Dq "ls -l" , 148but increases the lease load on the server. 149This is recommended unless the server is complaining about excessive 150lease load. 151.It Fl m 152Set the Kerberos realm to the string argument. 153Used with the 154.Fl K 155option for mounts to other realms. 156.It Fl o 157Options are specified with a 158.Fl o 159flag followed by a comma separated string of options. 160See the 161.Xr mount 8 162man page for possible options and their meanings. 163.It Fl q 164Use the leasing extensions to the protocol to maintain cache consistency. 165This protocol, referred to as Not Quite Nfs (NQNFS), 166is only supported by 4.4BSD servers. 167.It Fl r 168Set the read data size to the specified value. 169It should be a power of 2 greater than or equal to 1024. 170This should be used for UDP mounts when the 171.Dq "fragments dropped due to timeout" 172value is getting large while actively using a mount point. 173(Use 174.Xr netstat 1 175with the 176.Fl s 177option to see what the 178.Dq "fragments dropped due to timeout" 179value is.) 180See the 181.Fl w 182option as well. 183.It Fl s 184A soft mount, which implies that file system calls will fail 185after \fBRetry\fR round trip timeout intervals. 186.It Fl t 187Set the initial retransmit timeout to the specified value. 188May be useful for fine tuning UDP mounts over internetworks 189with high packet loss rates or an overloaded server. 190Try increasing the interval if 191.Xr nfsstat 1 192shows high retransmit rates while the file system is active or reducing the 193value if there is a low retransmit rate but long response delay observed. 194.It Fl w 195Set the write data size to the specified value. 196Ditto the comments w.r.t. the 197.Fl r 198option, but using the 199.Dq "fragments dropped due to timeout" 200value on the server instead of the client. 201Note that both the 202.Fl r 203and 204.Fl w 205options should only be used as a last ditch effort at improving performance 206when mounting servers that do not support TCP mounts. 207.It Fl x 208Set the retransmit timeout count for soft mounts to the specified value. 209.El 210.Sh SEE ALSO 211.Xr mount 2 , 212.Xr unmount 2 , 213.Xr fstab 5 , 214.Xr mount 8 215.Sh BUGS 216Due to the way that Sun RPC is implemented on top of UDP (unreliable datagram) 217transport, tuning such mounts is really a black art that can only be expected 218to have limited success. 219For clients mounting servers that are not on the same 220LAN cable or that tend to be overloaded, 221TCP transport is strongly recommended, 222but unfortunately this is restricted to mostly 4.4BSD servers. 223