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28 .\" @(#)mount_nfs.8 8.3 (Berkeley) 3/29/95
36 .Nd mount NFS file systems
40 .Op Fl a Ar maxreadahead
41 .Op Fl D Ar deadthresh
43 .Op Fl I Ar readdirsize
50 .Ar rhost : Ns Ar path node
56 system call to prepare and graft a remote NFS file system
57 .Pq Ar rhost : Ns Ar path
58 on to the file system tree at the point
60 This command is normally executed by
62 It implements the mount protocol as described in RFC 1094, Appendix A and
63 .%T "NFS: Network File System Version 3 Protocol Specification" ,
68 keeps retrying until the mount succeeds.
69 This behaviour is intended for file systems listed in
71 that are critical to the boot process.
72 For non-critical file systems, the
76 flags provide mechanisms to prevent the boot process from hanging
77 if the server is unavailable.
79 If the server becomes unresponsive while an NFS file system is
80 mounted, any new or outstanding file operations on that file system
81 will hang uninterruptibly until the server comes back.
82 To modify this default behaviour, see the
89 .Bl -tag -width indent
91 Use the NFS Version 2 protocol (the default is to try version 3 first
93 Note that NFS version 2 has a file size limit of 2 gigabytes.
95 Use the NFS Version 3 protocol.
97 Use the NFS Version 4 protocol.
100 .Dq "dead server threshold"
101 to the specified number of round trip timeout intervals before a
102 .Dq "server not responding"
103 message is displayed.
105 Set the readdir read size to the specified value.
106 The value should normally
109 that is <= the read size for the mount.
116 All locks will be local and not seen by the server
117 and likewise not seen by other NFS clients.
118 This removes the need to run the
124 servers on the client.
125 Note that this option will only be honored when performing the
126 initial mount, it will be silently ignored if used while updating
131 use a reserved socket port number (see below).
133 Use a reserved socket port number.
134 This flag is obsolete, and only retained for compatibility reasons.
135 Reserved port numbers are used by default now.
136 (For the rare case where the client has a trusted root account
137 but untrustworthy users and the network cables are in secure areas this does
138 help, but for normal desktop clients this does not apply.)
140 Set the mount retry count to the specified value.
141 The default is a retry count of zero, which means to keep retrying
143 There is a 60 second delay between each attempt.
145 Use TCP transport instead of UDP.
146 This is recommended for servers that are not on the same LAN cable as
148 Not all NFS servers support this method, especially older ones;
149 caution should be observed in these cases.
151 Force the mount protocol to use UDP transport, even for TCP NFS mounts.
152 (Necessary for some old
156 Set the read-ahead count to the specified value.
157 This may be in the range of 0 - 4, and determines how many blocks
158 will be read ahead when a large file is being read sequentially.
159 Trying a value greater than 1 for this is suggested for
160 mounts with a large bandwidth * delay product.
162 If an initial attempt to contact the server fails, fork off a child to keep
163 trying the mount in the background.
166 where the file system mount is not critical to multiuser operation.
168 For UDP mount points, do not do a
170 This must be used if the server does not reply to requests from the standard
171 NFS port number 2049 or replies to requests using a different IP address
172 (which can occur if the server is multi-homed).
174 .Va vfs.nfs.nfs_ip_paranoia
175 sysctl to 0 will make this option the default.
177 Turn off the dynamic retransmit timeout estimator.
178 This may be useful for UDP mounts that exhibit high retry rates,
179 since it is possible that the dynamically estimated timeout interval is too
182 Set the maximum size of the group list for the credentials to the
184 This should be used for mounts on old servers that cannot handle a
185 group list size of 16, as specified in RFC 1057.
186 Try 8, if users in a lot of groups cannot get response from the mount
189 Make the mount interruptible, which implies that file system calls that
190 are delayed due to an unresponsive server will fail with EINTR when a
191 termination signal is posted for the process.
193 Used with NQNFS and NFSV3 to specify that the \fBReaddirPlus\fR RPC should
195 This option reduces RPC traffic for cases such as
197 but tends to flood the attribute and name caches with prefetched entries.
198 Try this option and see whether performance improves or degrades.
200 most useful for client to server network interconnects with a large bandwidth
203 Options are specified with a
205 flag followed by a comma separated string of options.
208 man page for possible options and their meanings.
209 The following NFS specific options are also available:
210 .Bl -tag -width indent
211 .It Cm port Ns = Ns Aq Ar port_number
212 Use specified port number for NFS requests.
213 The default is to query the portmapper for the NFS port.
214 .It Cm acregmin Ns = Ns Aq Ar seconds
215 .It Cm acregmax Ns = Ns Aq Ar seconds
216 .It Cm acdirmin Ns = Ns Aq Ar seconds
217 .It Cm acdirmax Ns = Ns Aq Ar seconds
218 When attributes of files are cached, a timeout calculated to determine
219 whether a given cache entry has expired.
220 These four values determine the upper and lower bounds of the timeouts for
224 (ie: everything else).
225 The default values are 3 -> 60 seconds
226 for regular files, and 30 -> 60 seconds for directories.
227 The algorithm to calculate the timeout is based on the age of the file.
229 the longer the cache is considered valid, subject to the limits above.
230 .It Cm noinet4 , noinet6
236 Useful for hosts that have
237 both an A record and an AAAA record for the same name.
240 .Sy Historic Fl o Sy Options
242 Use of these options is deprecated, they are only mentioned here for
243 compatibility with historic versions of
245 .Bl -tag -width ".Cm dumbtimer"
250 Same as not specifying
253 Same as not specifying
262 Same as not specifying
283 Same as not specifying
290 Set the read data size to the specified value.
291 It should normally be a power of 2 greater than or equal to 1024.
292 This should be used for UDP mounts when the
293 .Dq "fragments dropped due to timeout"
294 value is getting large while actively using a mount point.
299 option to see what the
300 .Dq "fragments dropped due to timeout"
306 A soft mount, which implies that file system calls will fail
309 round trip timeout intervals.
311 Set the initial retransmit timeout to the specified value.
312 May be useful for fine tuning UDP mounts over internetworks
313 with high packet loss rates or an overloaded server.
314 Try increasing the interval if
316 shows high retransmit rates while the file system is active or reducing the
317 value if there is a low retransmit rate but long response delay observed.
320 option should be specified when using this option to manually
324 Set the write data size to the specified value.
325 Ditto the comments w.r.t.\& the
327 option, but using the
328 .Dq "fragments dropped due to timeout"
329 value on the server instead of the client.
334 options should only be used as a last ditch effort at improving performance
335 when mounting servers that do not support TCP mounts.
337 Set the retransmit timeout count for soft mounts to the specified value.