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