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8 .TH MOUNT_NFS 1M "Sep 8, 2015"
9 .SH NAME
10 mount_nfs \- mount remote NFS resources
11 .SH SYNOPSIS
12 .LP
13 .nf
14 \fBmount\fR [\fB-F\fR nfs] [\fIgeneric_options\fR] [\fB-o\fR \fIspecific_options\fR] [\fB-O\fR] \fIresource\fR
15 .fi
16
17 .LP
18 .nf
19 \fBmount\fR [\fB-F\fR nfs] [\fIgeneric_options\fR] [\fB-o\fR \fIspecific_options\fR] [\fB-O\fR] \fImount_point\fR
20 .fi
21
22 .LP
23 .nf
24 \fBmount\fR [\fB-F\fR nfs] [\fIgeneric_options\fR] [\fB-o\fR \fIspecific_options\fR]
25 [\fB-O\fR] \fIresource\fR \fImount_point\fR
26 .fi
27
28 .SH DESCRIPTION
29 .LP
30 The \fBmount\fR utility attaches a named \fIresource\fR to the file system
31 hierarchy at the pathname location \fImount_point\fR, which must already exist.
32 If \fImount_point\fR has any contents prior to the \fBmount\fR operation, the
33 contents remain hidden until the \fIresource\fR is once again unmounted.
34 .sp
35 .LP
36 \fBmount_nfs\fR starts the \fBlockd\fR(1M) and \fBstatd\fR(1M) daemons if they
37 are not already running.
38 .sp
39 .LP
40 If the resource is listed in the \fB/etc/vfstab\fR file, the command line can
41 specify either \fIresource\fR or \fImount_point\fR, and \fBmount\fR consults
42 \fB/etc/vfstab\fR for more information. If the \fB-F\fR option is omitted,
43 \fBmount\fR takes the file system type from \fB/etc/vfstab\fR.
44 .sp
45 .LP
46 If the resource is not listed in the \fB/etc/vfstab\fR file, then the command
47 line must specify both the \fIresource\fR and the \fImount_point\fR.
48 .sp
49 .LP
50 \fIhost\fR can be an IPv4 or IPv6 address string. As IPv6 addresses already
51 contain colons, enclose \fIhost\fR in a pair of square brackets when specifying
52 an IPv6 address string. Otherwise the first occurrence of a colon can be
53 interpreted as the separator between the host name and path, for example,
54 \fB[1080::8:800:200C:417A]:tmp/file\fR. See \fBinet\fR(7P) and \fBinet6\fR(7P).
55 .sp
56 .ne 2
57 .na
58 \fB\fIhost\fR:\fIpathname\fR\fR
59 .ad
60 .sp .6
61 .RS 4n
62 Where \fIhost\fR is the name of the \fBNFS\fR server host, and \fIpathname\fR
63 is the path name of the directory on the server being mounted. The path name is
64 interpreted according to the server's path name parsing rules and is not
65 necessarily slash-separated, though on most servers, this is the case.
66 .RE
67
68 .sp
69 .ne 2
70 .na
71 \fB\fInfs\fR://\fIhost\fR[:\fIport\fR]/\fIpathname\fR\fR
72 .ad
73 .sp .6
74 .RS 4n
75 This is an \fBNFS\fR \fBURL\fR and follows the standard convention for
76 \fBNFS\fR \fBURL\fRs as described in \fINFS URL Scheme\fR, RFC 2224. See the
77 discussion of \fBURL\fR's and the public option under \fBNFS FILE SYSTEMS\fR
78 for a more detailed discussion.
79 .RE
80
81 .sp
82 .ne 2
83 .na
84 \fB\fIhost\fR:\fIpathname\fR
85 \fInfs\fR://\fIhost\fR[:\fIport\fR]/\fIpathname\fR\fR
86 .ad
87 .br
88 .na
89 \fB\fR
90 .ad
91 .sp .6
92 .RS 4n
93 \fIhost\fR:\fIpathname\fR is a comma-separated list of
94 \fIhost\fR:\fIpathname\fR.
95 .sp
96 See the discussion of replicated file systems and failover under \fBNFS FILE
97 SYSTEMS\fR for a more detailed discussion.
98 .RE
99
100 .sp
101 .ne 2
102 .na
103 \fB\fIhostlist\fR \fIpathname\fR\fR
104 .ad
105 .sp .6
106 .RS 4n
107 \fIhostlist\fR is a comma-separated list of hosts.
108 .sp
109 See the discussion of replicated file systems and failover under \fBNFS FILE
110 SYSTEMS\fR for a more detailed discussion.
111 .RE
112
113 .sp
114 .LP
115 The \fBmount\fR command maintains a table of mounted file systems in
116 \fB/etc/mnttab\fR, described in \fBmnttab\fR(4).
117 .sp
118 .LP
119 \fBmount_nfs\fR supports both NFSv3 and NFSv4 mounts. The default NFS version
120 is NFSv4.
121 .SH OPTIONS
122 .LP
123 See \fBmount\fR(1M) for the list of supported \fIgeneric_options\fR. See
124 \fBshare_nfs\fR(1M) for a description of server options.
125 .sp
126 .ne 2
127 .na
128 \fB\fB-o\fR \fIspecific_options\fR\fR
129 .ad
130 .sp .6
131 .RS 4n
132 Set file system specific options according to a comma-separated list with no
133 intervening spaces.
134 .sp
135 .ne 2
136 .na
137 \fB\fBacdirmax=\fR\fIn\fR\fR
138 .ad
139 .sp .6
140 .RS 4n
141 Hold cached attributes for no more than \fIn\fR seconds after directory update.
142 The default value is \fB60\fR.
143 .RE
144
145 .sp
146 .ne 2
147 .na
148 \fB\fBacdirmin=\fR\fIn\fR\fR
149 .ad
150 .sp .6
151 .RS 4n
152 Hold cached attributes for at least \fIn\fR seconds after directory update. The
153 default value is \fB30\fR.
154 .RE
155
156 .sp
157 .ne 2
158 .na
159 \fB\fBacregmax=\fR\fIn\fR\fR
160 .ad
161 .sp .6
162 .RS 4n
163 Hold cached attributes for no more than \fIn\fR seconds after file
164 modification. The default value is \fB60\fR.
165 .RE
166
167 .sp
168 .ne 2
169 .na
170 \fB\fBacregmin=\fR\fIn\fR\fR
171 .ad
172 .sp .6
173 .RS 4n
174 Hold cached attributes for at least \fIn\fR seconds after file modification.
175 The default value is \fB3\fR.
176 .RE
177
178 .sp
179 .ne 2
180 .na
181 \fB\fBactimeo=\fR\fIn\fR\fR
182 .ad
183 .sp .6
184 .RS 4n
185 Set \fImin\fR and \fImax\fR times for regular files and directories to \fIn\fR
186 seconds. See "File Attributes," below, for a description of the effect of
187 setting this option to \fB0\fR.
188 .sp
189 See "Specifying Values for Attribute Cache Duration Options," below, for a
190 description of how \fBacdirmax\fR, \fBacdirmin\fR, \fBacregmax\fR,
191 \fBacregmin\fR, and \fBactimeo\fR are parsed on a \fBmount\fR command line.
192 .RE
193
194 .sp
195 .ne 2
196 .na
197 \fB\fBbg\fR | \fBfg\fR\fR
198 .ad
199 .sp .6
200 .RS 4n
201 If the first attempt fails, retry in the background, or, in the foreground. The
202 default is \fBfg\fR.
203 .RE
204
205 .sp
206 .ne 2
207 .na
208 \fB\fBforcedirectio\fR | \fBnoforcedirectio\fR\fR
209 .ad
210 .sp .6
211 .RS 4n
212 If \fBforcedirectio\fR is specified, then for the duration of the mount, forced
213 direct \fBI/O\fR is used. If the filesystem is mounted using
214 \fBforcedirectio\fR, data is transferred directly between client and server,
215 with no buffering on the client. If the filesystem is mounted using
216 \fBnoforcedirectio\fR, data is buffered on the client. \fBforcedirectio\fR is a
217 performance option that is of benefit only in large sequential data transfers.
218 The default behavior is \fBnoforcedirectio\fR.
219 .RE
220
221 .sp
222 .ne 2
223 .na
224 \fB\fBgrpid\fR\fR
225 .ad
226 .sp .6
227 .RS 4n
228 By default, the \fBGID\fR associated with a newly created file obeys the System
229 V semantics; that is, the \fBGID\fR is set to the effective \fBGID\fR of the
230 calling process. This behavior can be overridden on a per-directory basis by
231 setting the set-GID bit of the parent directory; in this case, the \fBGID\fR of
232 a newly created file is set to the \fBGID\fR of the parent directory (see
233 \fBopen\fR(2) and \fBmkdir\fR(2)). Files created on file systems that are
234 mounted with the \fBgrpid\fR option obeys \fBBSD\fR semantics independent of
235 whether the set-GID bit of the parent directory is set; that is, the \fBGID\fR
236 is unconditionally inherited from that of the parent directory.
237 .RE
238
239 .sp
240 .ne 2
241 .na
242 \fB\fBhard\fR | \fBsoft\fR\fR
243 .ad
244 .sp .6
245 .RS 4n
246 Continue to retry requests until the server responds (\fBhard\fR) or give up
247 and return an error (\fBsoft\fR). The default value is \fBhard\fR. Note that
248 NFSv4 clients do not support soft mounts.
249 .RE
250
251 .sp
252 .ne 2
253 .na
254 \fB\fBintr\fR | \fBnointr\fR\fR
255 .ad
256 .sp .6
257 .RS 4n
258 Allow (do not allow) keyboard interrupts to kill a process that is hung while
259 waiting for a response on a hard-mounted file system. The default is
260 \fBintr\fR, which makes it possible for clients to interrupt applications that
261 can be waiting for a remote mount.
262 .RE
263
264 .sp
265 .ne 2
266 .na
267 \fB\fBnoac\fR\fR
268 .ad
269 .sp .6
270 .RS 4n
271 Suppress data and attribute caching. The data caching that is suppressed is the
272 write-behind. The local page cache is still maintained, but data copied into it
273 is immediately written to the server.
274 .RE
275
276 .sp
277 .ne 2
278 .na
279 \fB\fBnocto\fR\fR
280 .ad
281 .sp .6
282 .RS 4n
283 Do not perform the normal close-to-open consistency. When a file is closed, all
284 modified data associated with the file is flushed to the server and not held on
285 the client. When a file is opened the client sends a request to the server to
286 validate the client's local caches. This behavior ensures a file's consistency
287 across multiple NFS clients. When \fB-nocto\fR is in effect, the client does
288 not perform the flush on close and the request for validation, allowing the
289 possiblity of differences among copies of the same file as stored on multiple
290 clients.
291 .sp
292 This option can be used where it can be guaranteed that accesses to a specified
293 file system are made from only one client and only that client. Under such a
294 condition, the effect of \fB-nocto\fR can be a slight performance gain.
295 .RE
296
297 .sp
298 .ne 2
299 .na
300 \fB\fBport=\fR\fIn\fR\fR
301 .ad
302 .sp .6
303 .RS 4n
304 The server \fBIP\fR port number. The default is \fBNFS_PORT\fR. If the
305 \fBport\fR option is specified, and if the resource includes one or more
306 \fBNFS\fR \fBURL\fRs, and if any of the \fBURL\fRs include a \fBport\fR number,
307 then the \fBport\fR number in the option and in the \fBURL\fR must be the same.
308 .RE
309
310 .sp
311 .ne 2
312 .na
313 \fB\fBposix\fR\fR
314 .ad
315 .sp .6
316 .RS 4n
317 Request \fBPOSIX.1\fR semantics for the file system. Requires a mount Version 2
318 \fBmountd\fR(1M) on the server. See \fBstandards\fR(5) for information
319 regarding POSIX.
320 .RE
321
322 .sp
323 .ne 2
324 .na
325 \fB\fBproto=\fR\fInetid\fR | \fBrdma\fR\fR
326 .ad
327 .sp .6
328 .RS 4n
329 By default, the transport protocol that the NFS mount uses is the first
330 available RDMA transport supported both by the client and the server. If no
331 RDMA transport is found, then it attempts to use a TCP transport or, failing
332 that, a UDP transport, as ordered in the \fB/etc/netconfig\fR file. If it does
333 not find a connection oriented transport, it uses the first available
334 connectionless transport.
335 .sp
336 Use this option to override the default behavior.
337 .sp
338 \fBproto\fR is set to the value of \fInetid\fR or \fBrdma\fR. \fInetid\fR is
339 the value of the \fBnetwork_id\fR field entry in the \fB/etc/netconfig\fR file.
340 .sp
341 The UDP protocol is not supported for NFS Version 4. If you specify a UDP
342 protocol with the \fBproto\fR option, NFS version 4 is not used.
343 .RE
344
345 .sp
346 .ne 2
347 .na
348 \fB\fBpublic\fR\fR
349 .ad
350 .sp .6
351 .RS 4n
352 The \fBpublic\fR option forces the use of the public file handle when
353 connecting to the \fBNFS\fR server. The resource specified might not have an
354 \fBNFS\fR \fBURL\fR. See the discussion of \fBURL\fRs and the public option
355 under \fBNFS FILE SYSTEMS\fR for a more detailed discussion.
356 .RE
357
358 .sp
359 .ne 2
360 .na
361 \fB\fBquota\fR | \fBnoquota\fR\fR
362 .ad
363 .sp .6
364 .RS 4n
365 Enable or prevent \fBquota\fR(1M) to check whether the user is over quota on
366 this file system; if the file system has quotas enabled on the server, quotas
367 are still checked for operations on this file system.
368 .RE
369
370 .sp
371 .ne 2
372 .na
373 \fB\fBremount\fR\fR
374 .ad
375 .sp .6
376 .RS 4n
377 Remounts a read-only file system as read-write (using the \fBrw\fR option).
378 This option cannot be used with other \fB-o\fR options, and this option works
379 only on currently mounted read-only file systems.
380 .RE
381
382 .sp
383 .ne 2
384 .na
385 \fB\fBretrans=\fR\fIn\fR\fR
386 .ad
387 .sp .6
388 .RS 4n
389 Set the number of \fBNFS\fR retransmissions to \fIn\fR. The default value is
390 \fB5\fR. For connection-oriented transports, this option has no effect because
391 it is assumed that the transport performs retransmissions on behalf of NFS.
392 .RE
393
394 .sp
395 .ne 2
396 .na
397 \fB\fBretry=\fR\fIn\fR\fR
398 .ad
399 .sp .6
400 .RS 4n
401 The number of times to retry the \fBmount\fR operation. The default for the
402 \fBmount\fR command is \fB10000\fR.
403 .sp
404 The default for the automounter is \fB0\fR, in other words, do not retry. You
405 might find it useful to increase this value on heavily loaded servers, where
406 automounter traffic is dropped, causing unnecessary server not responding
407 errors.
408 .RE
409
410 .sp
411 .ne 2
412 .na
413 \fB\fBrsize=\fR\fIn\fR\fR
414 .ad
415 .sp .6
416 .RS 4n
417 Set the read buffer size to a maximum of \fIn\fR bytes. The default value is
418 \fB1048576\fR when using connection-oriented transports with Version 3 or
419 Version 4 of the \fBNFS\fR protocol, and \fB32768\fR when using connection-less
420 transports. The default can be negotiated down if the server prefers a smaller
421 transfer size. "\fBRead\fR" operations may not necessarily use the maximum
422 buffer size. When using Version 2, the default value is \fB32768\fR for all
423 transports.
424 .RE
425
426 .sp
427 .ne 2
428 .na
429 \fB\fBsec=\fR\fImode\fR\fR
430 .ad
431 .sp .6
432 .RS 4n
433 Set the security \fImode\fR for \fBNFS\fR transactions. If \fBsec=\fR is not
434 specified, then the default action is to use \fBAUTH_SYS\fR over \fBNFS\fR
435 Version 2 mounts, use a user-configured default \fBauth\fR over NFS version 3
436 mounts, or to negotiate a mode over Version 4 mounts.
437 .sp
438 The preferred mode for NFS Version 3 mounts is the default mode specified in
439 \fB/etc/nfssec.conf\fR (see \fBnfssec.conf\fR(4)) on the client. If there is no
440 default configured in this file or if the server does not export using the
441 client's default mode, then the client picks the first mode that it supports in
442 the array of modes returned by the server. These alternatives are limited to
443 the security flavors listed in \fB/etc/nfssec.conf\fR.
444 .sp
445 NFS Version 4 mounts negotiate a security mode when the server returns an array
446 of security modes. The client attempts the mount with each security mode, in
447 order, until one is successful.
448 .sp
449 Only one mode can be specified with the \fBsec=\fR option. See \fBnfssec\fR(5)
450 for the available \fImode\fR options.
451 .RE
452
453 .sp
454 .ne 2
455 .na
456 \fB\fBsecure\fR\fR
457 .ad
458 .sp .6
459 .RS 4n
460 This option has been deprecated in favor of the \fBsec=\fR\fIdh\fR option.
461 .RE
462
463 .sp
464 .ne 2
465 .na
466 \fB\fBtimeo=\fR\fIn\fR\fR
467 .ad
468 .sp .6
469 .RS 4n
470 Set the \fBNFS\fR timeout to \fIn\fR tenths of a second. The default value is
471 \fB11\fR tenths of a second for connectionless transports, and \fB600\fR tenths
472 of a second for connection-oriented transports. This value is ignored for
473 connectionless transports. Such transports might implement their own timeouts,
474 which are outside the control of NFS.
475 .RE
476
477 .sp
478 .ne 2
479 .na
480 \fB\fBvers=\fR\fINFS version number\fR\fR
481 .ad
482 .sp .6
483 .RS 4n
484 By default, the version of \fBNFS\fR protocol used between the client and the
485 server is the highest one available on both systems. The default maximum for
486 the client is Version 4. This can be changed by setting the
487 \fBNFS_CLIENT_VERSMAX\fR parameter in \fB/etc/default/nfs\fR to a valid version
488 (2, 3, or 4). If the \fBNFS\fR server does not support the client's default
489 maximum, the next lowest version attempted until a matching version is found.
490 .RE
491
492 .sp
493 .ne 2
494 .na
495 \fB\fBwsize=\fR\fIn\fR\fR
496 .ad
497 .sp .6
498 .RS 4n
499 Set the write buffer size to a maximum of \fIn\fR bytes. The default value is
500 \fB1048576\fR when using connection-oriented transports with Version 3 or
501 Version 4 of the \fBNFS\fR protocol, and \fB32768\fR when using connection-less
502 transports. The default can be negotiated down if the server prefers a smaller
503 transfer size. "\fBWrite\fR" operations may not necessarily use the maximum
504 buffer size. When using Version 2, the default value is \fB32768\fR for all
505 transports.
506 .RE
507
508 .sp
509 .ne 2
510 .na
511 \fB\fBxattr\fR | \fBnoxattr\fR\fR
512 .ad
513 .sp .6
514 .RS 4n
515 Allow or disallow the creation and manipulation of extended attributes. The
516 default is \fBxattr\fR. See \fBfsattr\fR(5) for a description of extended
517 attributes.
518 .RE
519
520 .RE
521
522 .sp
523 .ne 2
524 .na
525 \fB\fB-O\fR\fR
526 .ad
527 .sp .6
528 .RS 4n
529 Overlay mount. Allow the file system to be mounted over an existing mount
530 point, making the underlying file system inaccessible. If a mount is attempted
531 on a pre-existing mount point without setting this flag, the mount fails,
532 producing the error "device busy."
533 .RE
534
535 .SH NFS FILE SYSTEMS
536 .ne 2
537 .na
538 \fBBackground versus Foreground\fR
539 .ad
540 .sp .6
541 .RS 4n
542 File systems mounted with the \fBbg\fR option indicate that \fBmount\fR is to
543 retry in the background if the server's mount daemon (\fBmountd\fR(1M)) does
544 not respond. \fBmount\fR retries the request up to the count specified in the
545 \fBretry=\fR\fIn\fR option. (Note that the default value for \fBretry\fR
546 differs between \fBmount\fR and \fBautomount\fR. See the description of
547 \fBretry\fR, above.) Once the file system is mounted, each \fBNFS\fR request
548 made in the kernel waits \fBtimeo=\fR\fIn\fR tenths of a second for a response.
549 If no response arrives, the time-out is multiplied by \fB2\fR and the request
550 is retransmitted. When the number of retransmissions has reached the number
551 specified in the \fBretrans=\fR\fIn\fR option, a file system mounted with the
552 \fBsoft\fR option returns an error on the request; one mounted with the
553 \fBhard\fR option prints a warning message and continues to retry the request.
554 .RE
555
556 .sp
557 .ne 2
558 .na
559 \fBHard versus Soft\fR
560 .ad
561 .sp .6
562 .RS 4n
563 File systems that are mounted read-write or that contain executable files
564 should always be mounted with the \fBhard\fR option. Applications using
565 \fBsoft\fR mounted file systems can incur unexpected \fBI/O\fR errors, file
566 corruption, and unexpected program core dumps. The soft option is not
567 recommended.
568 .RE
569
570 .sp
571 .ne 2
572 .na
573 \fBAuthenticated requests\fR
574 .ad
575 .sp .6
576 .RS 4n
577 The server can require authenticated \fBNFS\fR requests from the client.
578 \fBsec=\fR\fIdh\fR authentication might be required. See \fBnfssec\fR(5).
579 .RE
580
581 .sp
582 .ne 2
583 .na
584 \fBURLs and the public option\fR
585 .ad
586 .sp .6
587 .RS 4n
588 If the \fBpublic\fR option is specified, or if the \fIresource\fR includes and
589 \fBNFS\fR \fBURL\fR, \fBmount\fR attempts to connect to the server using the
590 public file handle lookup protocol. See \fIWebNFS Client Specification\fR, RFC
591 2054. If the server supports the public file handle, the attempt is successful;
592 \fBmount\fR does not need to contact the server's \fBrpcbind\fR(1M) and the
593 \fBmountd\fR(1M) daemons to get the port number of the \fBmount\fR server and
594 the initial file handle of \fIpathname\fR, respectively. If the \fBNFS\fR
595 client and server are separated by a firewall that allows all outbound
596 connections through specific ports, such as \fBNFS_PORT\fR, then this enables
597 \fBNFS\fR operations through the firewall. The public option and the \fBNFS\fR
598 \fBURL\fR can be specified independently or together. They interact as
599 specified in the following matrix:
600 .sp
601 .in +2
602 .nf
603 Resource Style
604
605 \fIhost\fR:\fIpathname\fR NFS URL
606
607 public option Force public file Force public file
608 handle and fail handle and fail
609 mount if not supported. mount if not supported.
610
611 Use Native paths. Use Canonical paths.
612
613 default Use MOUNT protocol. Try public file handle
614 with Canonical paths.
615 Fall back to MOUNT
616 protocol if not
617 supported.
618 .fi
619 .in -2
620
621 A Native path is a path name that is interpreted according to conventions used
622 on the native operating system of the \fBNFS\fR server. A Canonical path is a
623 path name that is interpreted according to the \fBURL\fR rules. See \fIUniform
624 Resource Locators (URL)\fR, RFC 1738. See for uses of Native and Canonical
625 paths.
626 .RE
627
628 .sp
629 .ne 2
630 .na
631 \fBReplicated file systems and failover\fR
632 .ad
633 .sp .6
634 .RS 4n
635 \fIresource\fR can list multiple read\(mionly file systems to be used to
636 provide data. These file systems should contain equivalent directory structures
637 and identical files. It is also recommended that they be created by a utility
638 such as \fBrdist\fR(1). The file systems can be specified either with a
639 comma\(miseparated list of \fIhost:/pathname\fR entries and/or \fBNFS\fR
640 \fBURL\fR entries, or with a comma \(miseparated list of hosts, if all file
641 system names are the same. If multiple file systems are named and the first
642 server in the list is down, failover uses the next alternate server to access
643 files. If the read\(mionly option is not chosen, replication is disabled. File
644 access, for NFS Versions 2 and 3, is blocked on the original if NFS locks are
645 active for that file.
646 .RE
647
648 .SS "File Attributes"
649 .LP
650 To improve \fBNFS\fR read performance, files and file attributes are cached.
651 File modification times get updated whenever a write occurs. However, file
652 access times can be temporarily out-of-date until the cache gets refreshed.
653 .sp
654 .LP
655 The attribute cache retains file attributes on the client. Attributes for a
656 file are assigned a time to be flushed. If the file is modified before the
657 flush time, then the flush time is extended by the time since the last
658 modification (under the assumption that files that changed recently are likely
659 to change soon). There is a minimum and maximum flush time extension for
660 regular files and for directories. Setting \fBactimeo=\fR\fIn\fR sets flush
661 time to \fIn\fR seconds for both regular files and directories.
662 .sp
663 .LP
664 Setting \fBactimeo=0\fR disables attribute caching on the client. This means
665 that every reference to attributes is satisfied directly from the server though
666 file data is still cached. While this guarantees that the client always has the
667 latest file attributes from the server, it has an adverse effect on performance
668 through additional latency, network load, and server load.
669 .sp
670 .LP
671 Setting the \fBnoac\fR option also disables attribute caching, but has the
672 further effect of disabling client write caching. While this guarantees that
673 data written by an application is written directly to a server, where it can be
674 viewed immediately by other clients, it has a significant adverse effect on
675 client write performance. Data written into memory-mapped file pages
676 (\fBmmap\fR(2)) are not written directly to this server.
677 .SS "Specifying Values for Attribute Cache Duration Options"
678 .LP
679 The attribute cache duration options are \fBacdirmax\fR, \fBacdirmin\fR,
680 \fBacregmax\fR, \fBacregmin\fR, and \fBactimeo\fR, as described under OPTIONS.
681 A value specified for \fBactimeo\fR sets the values of all attribute cache
682 duration options except for any of these options specified following
683 \fBactimeo\fR on a \fBmount\fR command line. For example, consider the
684 following command:
685 .sp
686 .in +2
687 .nf
688 example# mount -o acdirmax=10,actimeo=1000 server:/path /localpath
689 .fi
690 .in -2
691
692 .sp
693 .LP
694 Because \fBactimeo\fR is the last duration option in the command line, its
695 value (\fB1000\fR) becomes the setting for all of the duration options,
696 including \fBacdirmax\fR. Now consider:
697 .sp
698 .in +2
699 .nf
700 example# mount -o actimeo=1000,acdirmax=10 server:/path /localpath
701 .fi
702 .in -2
703
704 .sp
705 .LP
706 Because the \fBacdirmax\fR option follows \fBactimeo\fR on the command line, it
707 is assigned the value specified (\fB10\fR). The remaining duration options are
708 set to the value of \fBactimeo\fR (\fB1000\fR).
709 .SH EXAMPLES
710 .LP
711 \fBExample 1 \fRMounting an \fBNFS\fR File System
712 .sp
713 .LP
714 To mount an \fBNFS\fR file system:
715
716 .sp
717 .in +2
718 .nf
719 example# mount serv:/usr/src /usr/src
720 .fi
721 .in -2
722 .sp
723
724 .LP
725 \fBExample 2 \fRMounting An \fBNFS\fR File System Read-Only With No suid
726 Privileges
727 .sp
728 .LP
729 To mount an \fBNFS\fR file system read-only with no suid privileges:
730
731 .sp
732 .in +2
733 .nf
734 example# mount -r -o nosuid serv:/usr/src /usr/src
735 .fi
736 .in -2
737 .sp
738
739 .LP
740 \fBExample 3 \fRMounting An \fBNFS\fR File System Over Version 2, with the UDP
741 Transport
742 .sp
743 .LP
744 To mount an \fBNFS\fR file system over Version 2, with the UDP transport:
745
746 .sp
747 .in +2
748 .nf
749 example# mount -o vers=2,proto=udp serv:/usr/src /usr/src
750 .fi
751 .in -2
752 .sp
753
754 .LP
755 \fBExample 4 \fRMounting an \fBNFS\fR File System Using An \fBNFS\fR \fBURL\fR
756 .sp
757 .LP
758 To mount an \fBNFS\fR file system using an \fBNFS\fR \fBURL\fR (a canonical
759 path):
760
761 .sp
762 .in +2
763 .nf
764 example# mount nfs://serv/usr/man /usr/man
765 .fi
766 .in -2
767 .sp
768
769 .LP
770 \fBExample 5 \fRMounting An \fBNFS\fR File System Forcing Use Of The Public
771 File Handle
772 .sp
773 .LP
774 To mount an \fBNFS\fR file system and force the use of the public file handle
775 and an \fBNFS\fR \fBURL\fR (a canonical path) that has a non 7-bit ASCII escape
776 sequence:
777
778 .sp
779 .in +2
780 .nf
781 example# mount -o public nfs://serv/usr/%A0abc /mnt/test
782 .fi
783 .in -2
784 .sp
785
786 .LP
787 \fBExample 6 \fRMounting an \fBNFS\fR File System Using a Native Path
788 .sp
789 .LP
790 To mount an \fBNFS\fR file system using a native path (where the server uses
791 colons (":") as the component separator) and the public file handle:
792
793 .sp
794 .in +2
795 .nf
796 example# mount -o public serv:C:doc:new /usr/doc
797 .fi
798 .in -2
799 .sp
800
801 .LP
802 \fBExample 7 \fRMounting a Replicated Set of \fBNFS\fR File Systems with the
803 Same Pathnames
804 .sp
805 .LP
806 To mount a replicated set of \fBNFS\fR file systems with the same pathnames:
807
808 .sp
809 .in +2
810 .nf
811 example# mount serv\(mia,serv\(mib,serv\(mic:/usr/man /usr/man
812 .fi
813 .in -2
814 .sp
815
816 .LP
817 \fBExample 8 \fRMounting a Replicated Set of \fBNFS\fR File Systems with
818 Different Pathnames
819 .sp
820 .LP
821 To mount a replicated set of \fBNFS\fR file systems with different pathnames:
822
823 .sp
824 .in +2
825 .nf
826 example# mount serv\(mix:/usr/man,serv\(miy:/var/man,nfs://serv-z/man /usr/man
827 .fi
828 .in -2
829 .sp
830
831 .SH FILES
832 .ne 2
833 .na
834 \fB\fB/etc/mnttab\fR\fR
835 .ad
836 .sp .6
837 .RS 4n
838 table of mounted file systems
839 .RE
840
841 .sp
842 .ne 2
843 .na
844 \fB\fB/etc/dfs/fstypes\fR\fR
845 .ad
846 .sp .6
847 .RS 4n
848 default distributed file system type
849 .RE
850
851 .sp
852 .ne 2
853 .na
854 \fB\fB/etc/vfstab\fR\fR
855 .ad
856 .sp .6
857 .RS 4n
858 table of automatically mounted resources
859 .RE
860
861 .SH SEE ALSO
862 .LP
863 \fBrdist\fR(1), \fBlockd\fR(1M), \fBmountall\fR(1M), \fBmountd\fR(1M),
864 \fBnfsd\fR(1M), \fBquota\fR(1M), \fBstatd\fR(1M), \fBmkdir\fR(2),
865 \fBmmap\fR(2), \fBmount\fR(2), \fBopen\fR(2), \fBumount\fR(2), \fBmnttab\fR(4),
866 \fBnfs\fR(4), \fBnfssec.conf\fR(4), \fBattributes\fR(5), \fBfsattr\fR(5),
867 \fBnfssec\fR(5), \fBstandards\fR(5), \fBinet\fR(7P), \fBinet6\fR(7P),
868 \fBlofs\fR(7FS)
869 .sp
870 .LP
871 Callaghan, Brent, \fIWebNFS Client Specification\fR, RFC 2054, October 1996.
872 .sp
873 .LP
874 Callaghan, Brent, \fINFS URL Scheme\fR, RFC 2224, October 1997.
875 .sp
876 .LP
877 Berners-Lee, Masinter & McCahill , \fIUniform Resource Locators (URL)\fR, RFC
878 1738, December 1994.
879 .SH NOTES
880 .LP
881 An \fBNFS\fR server should not attempt to mount its own file systems. See
882 \fBlofs\fR(7FS).
883 .sp
884 .LP
885 If the directory on which a file system is to be mounted is a symbolic link,
886 the file system is mounted on \fBthe directory to which the symbolic link
887 refers,\fR rather than being mounted on top of the symbolic link itself.
888 .sp
889 .LP
890 SunOS 4.x used the \fBbiod\fR maintenance procedure to perform parallel
891 read-ahead and write-behind on \fBNFS\fR clients. SunOS 5.x made \fBbiod\fR
892 obsolete with multi-threaded processing, which transparently performs parallel
893 read-ahead and write-behind.
894 .sp
895 .LP
896 Since the root \fB(\fR/\fB)\fR file system is mounted read-only by the kernel
897 during the boot process, only the \fBremount\fR option (and options that can be
898 used in conjunction with \fBremount\fR) affect the root (\fB/\fR) entry in the
899 \fB/etc/vfstab\fR file.
900 .sp
901 .LP
902 The NFS client service is managed by the service management facility,
903 \fBsmf\fR(5), under the service identifier:
904 .sp
905 .in +2
906 .nf
907 svc:/network/nfs/client:default
908 .fi
909 .in -2
910 .sp
911
912 .sp
913 .LP
914 Administrative actions on this service, such as enabling, disabling, or
915 requesting restart, can be performed using \fBsvcadm\fR(1M). The service's
916 status can be queried using the \fBsvcs\fR(1) command.