1.\" Copyright (c) 1992 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)mount_nfs.8 5.1 (Berkeley) 01/06/92 7.\" 8.Dd 9.Dt MOUNT_NFS 8 10.Os BSD 4.4 11.Sh NAME 12.Nm mount_nfs 13.Nd mount nfs file systems 14.Sh SYNOPSIS 15.Nm mount_nfs 16.Op Fl bsiTMlqdckK 17.Op Fl R Ar retrycnt 18.Op Fl r Ar readsize 19.Op Fl w Ar writesize 20.Op Fl t Ar timeout 21.Op Fl x Ar retrans 22.Op Fl g Ar maxgroups 23.Op Fl a Ar maxreadahead 24.Op Fl L Ar leaseterm 25.Op Fl D Ar deadthresh 26.Op Fl m Ar realm 27.Ar rhost:path node 28.Sh DESCRIPTION 29The 30.Nm mount_nfs 31command 32calls the 33.Xr mount 2 34system call to prepare and graft a 35remote nfs file system 36(rhost:path) 37on to the file system tree at the point 38.Ar node. 39This command is normally executed by 40.Xr mount 8 41setting the options with the 42.Fl o 43flag. 44It implements the mount protocol as described in RFC 1094, Appendix A. 45.Pp 46The options are: 47.Bl -tag -width indent 48.It Fl b 49If an initial attempt to contact the server fails, fork off a child to keep 50trying the mount in the background. Useful for 51.Xr fstab 5 52where the filesystem mount is not critical to multiuser operation. 53.It Fl s 54A soft mount, which implies that file system calls will fail 55after \fBRetry\fR round trip timeout intervals. 56.It Fl i 57An interruptible mount, which implies that file system calls that are delayed 58due to an unresponsive server will fail with EINTR when a termination signal 59is posted for the process. 60.It Fl T 61Use TCP transport instead of UDP. 62This is recommended for servers that are not on the 63same LAN cable as the client. 64(NB: This is NOT supported by most non-BSD servers.) 65.It Fl M 66Assume that other clients are not writing a file concurrently with this client. 67This implements a slightly less strict 68consistency criteria than 4.3BSD Reno did, 69that is more in line with most commercial client implementations. 70This is recommended for servers that do not support leasing. 71.It Fl d 72Do not estimate retransmit timeout dynamically. 73This may be useful for UDP 74mounts that exhibit high retry rates. 75.It Fl c 76For UDP mount points, do not do a 77.Xr connect 2. 78This must be used for servers that do not reply to requests from the standard 79port number. 80.It Fl K 81Pass Kerberos authenticators to the server for 82client-to-server user-credential mapping. 83This may only be used over TCP mounts between 4.4BSD clients and 84servers. 85.It Fl q 86Use the leasing extensions to the protocol to maintain cache consistency. 87This protocol, referred to as Not Quite Nfs (NQNFS), 88is only supported by 4.4BSD servers. 89.It Fl l 90Used with NQNFS to specify that the 91\fBReaddir_and_Lookup\fR RPC should be used. 92This option reduces RPC traffic for cases such as ``ls -l'', 93but increases the lease load on the server. 94This is recommended unless the server is complaining 95about excessive lease load. 96.It Fl k 97Used with NQNFS to specify ``get a lease'' for the file name being looked up. 98This is recommended unless the server is complaining about excessive lease 99load. 100.El 101.Pp 102The following arguments take a value parameter that is either a decimal 103number or a character string specified as =<value> after the option flag. 104.Bl -tag -width indent 105.It Fl R 106Set the retry count for doing the mount to <value>. 107.It Fl x 108Set the retransmit timeout count for soft mounts to <value>. 109.It Fl r 110Set the read data size to <value>. 111It should be a power of 2 greater than 512. 112This should be used for UDP mounts when the 113``fragments dropped due to timeout'' 114value is getting large while actively using a mount point. 115(Use 116.Xr netstat 1 117with the 118.FL s 119option to see what the ``fragments dropped due to timeout'' value is.) 120.It Fl w 121Set the write data size to <value>. 122Ditto the comments w.r.t. the 123.Fl r 124option, but using the ``fragments dropped due to timeout'' value on the 125server instead of the client. 126Note that both the 127.Fl r 128and 129.Fl w 130options should only be used as a last ditch effort at improving performance 131when mounting servers that do not support TCP mounts. 132.It Fl t 133Set the initial retransmit timeout to <value>. 134May be useful for fine tuning UDP mounts over internetworks 135with high packet loss rates or an overloaded server. 136Try increasing the interval if 137.Xr nfsstat 1 138shows high retransmit rates while the file system is active or reducing the 139value if there is a low retransmit rate but long response delay observed. 140.It Fl g 141Set the maximum size of the group list for the credentials to <value>. 142This should be used for mounts on old servers that cannot handle a group list 143size of 16, as specified in RFC 1057. 144Try 8, if users in a lot of groups 145cannot get response from the mount point. 146.It Fl a 147Set the read-ahead count to <value>. 148This may be in the range of 0 - 4 and determines how many blocks 149will be read ahead when a large file is being read sequentially. 150This is recommended for mounts with a large 151bandwidth * delay product. 152.It Fl L 153Used with NQNFS to set the lease term to <value> seconds. 154Only use this argument for mounts with a large round trip delay. 155Values are normally in the 10-30 second range. 156.It Fl D 157Used with NQNFS to set the ``dead server threshold'' to <value> round trip 158timeout intervals. 159After a ``dead server threshold'' of retransmit timeouts, 160cached data for the unresponsive server is assumed to still be valid. 161Values may be set in the range of 1 - 9, with 9 referring to an ``infinite 162dead threshold'' (i.e. never assume cached data still valid). 163This option is not generally recommended and 164is really an experimental feature. 165.It Fl m 166Set the Kerberos realm to the string argument. Used with the 167.Fl K 168option for mounts to other realms. 169.El 170.Sh SEE ALSO 171.Xr mount 2 , 172.Xr unmount 2 , 173.Xr fstab 5 174.Sh BUGS 175Due to the way that Sun RPC is implemented on top of UDP (unreliable datagram) 176transport, tuning such mounts is really a black art that can only be expected 177to have limited success. 178For clients mounting servers that are not on the same 179LAN cable or that tend to be overloaded, 180TCP transport is strongly recommended, 181but unfortunately this is restricted to mostly 4.4BSD servers. 182