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7 .TH MOUNT_NFS 1M "Jul 26, 2009"
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 .sp
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 .sp
123 .LP
124 See \fBmount\fR(1M) for the list of supported \fIgeneric_options\fR. See
125 \fBshare_nfs\fR(1M) for a description of server options.
126 .sp
127 .ne 2
128 .na
129 \fB\fB-o\fR \fIspecific_options\fR\fR
130 .ad
131 .sp .6
132 .RS 4n
133 Set file system specific options according to a comma-separated list with no
134 intervening spaces.
135 .sp
136 .ne 2
137 .na
138 \fB\fBacdirmax=\fR\fIn\fR\fR
139 .ad
140 .sp .6
141 .RS 4n
142 Hold cached attributes for no more than \fIn\fR seconds after directory update.
143 The default value is \fB60\fR.
144 .RE
145
146 .sp
147 .ne 2
148 .na
149 \fB\fBacdirmin=\fR\fIn\fR\fR
150 .ad
151 .sp .6
152 .RS 4n
153 Hold cached attributes for at least \fIn\fR seconds after directory update. The
154 default value is \fB30\fR.
155 .RE
156
157 .sp
158 .ne 2
159 .na
160 \fB\fBacregmax=\fR\fIn\fR\fR
161 .ad
162 .sp .6
163 .RS 4n
164 Hold cached attributes for no more than \fIn\fR seconds after file
165 modification. The default value is \fB60\fR.
166 .RE
167
168 .sp
169 .ne 2
170 .na
171 \fB\fBacregmin=\fR\fIn\fR\fR
172 .ad
173 .sp .6
174 .RS 4n
175 Hold cached attributes for at least \fIn\fR seconds after file modification.
176 The default value is \fB3\fR.
177 .RE
178
179 .sp
180 .ne 2
181 .na
182 \fB\fBactimeo=\fR\fIn\fR\fR
183 .ad
184 .sp .6
185 .RS 4n
186 Set \fImin\fR and \fImax\fR times for regular files and directories to \fIn\fR
187 seconds. See "File Attributes," below, for a description of the effect of
188 setting this option to \fB0\fR.
189 .sp
190 See "Specifying Values for Attribute Cache Duration Options," below, for a
191 description of how \fBacdirmax\fR, \fBacdirmin\fR, \fBacregmax\fR,
192 \fBacregmin\fR, and \fBactimeo\fR are parsed on a \fBmount\fR command line.
193 .RE
194
195 .sp
196 .ne 2
197 .na
198 \fB\fBbg\fR | \fBfg\fR\fR
199 .ad
200 .sp .6
201 .RS 4n
202 If the first attempt fails, retry in the background, or, in the foreground. The
203 default is \fBfg\fR.
204 .RE
205
206 .sp
207 .ne 2
208 .na
209 \fB\fBforcedirectio\fR | \fBnoforcedirectio\fR\fR
210 .ad
211 .sp .6
212 .RS 4n
213 If \fBforcedirectio\fR is specified, then for the duration of the mount, forced
214 direct \fBI/O\fR is used. If the filesystem is mounted using
215 \fBforcedirectio\fR, data is transferred directly between client and server,
216 with no buffering on the client. If the filesystem is mounted using
217 \fBnoforcedirectio\fR, data is buffered on the client. \fBforcedirectio\fR is a
218 performance option that is of benefit only in large sequential data transfers.
219 The default behavior is \fBnoforcedirectio\fR.
220 .RE
221
222 .sp
223 .ne 2
224 .na
225 \fB\fBgrpid\fR\fR
226 .ad
227 .sp .6
228 .RS 4n
229 By default, the \fBGID\fR associated with a newly created file obeys the System
230 V semantics; that is, the \fBGID\fR is set to the effective \fBGID\fR of the
231 calling process. This behavior can be overridden on a per-directory basis by
232 setting the set-GID bit of the parent directory; in this case, the \fBGID\fR of
233 a newly created file is set to the \fBGID\fR of the parent directory (see
234 \fBopen\fR(2) and \fBmkdir\fR(2)). Files created on file systems that are
235 mounted with the \fBgrpid\fR option obeys \fBBSD\fR semantics independent of
236 whether the set-GID bit of the parent directory is set; that is, the \fBGID\fR
237 is unconditionally inherited from that of the parent directory.
238 .RE
239
240 .sp
241 .ne 2
242 .na
243 \fB\fBhard\fR | \fBsoft\fR\fR
244 .ad
245 .sp .6
246 .RS 4n
247 Continue to retry requests until the server responds (\fBhard\fR) or give up
248 and return an error (\fBsoft\fR). The default value is \fBhard\fR. Note that
249 NFSv4 clients do not support soft mounts.
250 .RE
251
252 .sp
253 .ne 2
254 .na
255 \fB\fBintr\fR | \fBnointr\fR\fR
256 .ad
257 .sp .6
258 .RS 4n
259 Allow (do not allow) keyboard interrupts to kill a process that is hung while
260 waiting for a response on a hard-mounted file system. The default is
261 \fBintr\fR, which makes it possible for clients to interrupt applications that
262 can be waiting for a remote mount.
263 .RE
264
265 .sp
266 .ne 2
267 .na
268 \fB\fBnoac\fR\fR
269 .ad
270 .sp .6
271 .RS 4n
272 Suppress data and attribute caching. The data caching that is suppressed is the
273 write-behind. The local page cache is still maintained, but data copied into it
274 is immediately written to the server.
275 .RE
276
277 .sp
278 .ne 2
279 .na
280 \fB\fBnocto\fR\fR
281 .ad
282 .sp .6
283 .RS 4n
284 Do not perform the normal close-to-open consistency. When a file is closed, all
285 modified data associated with the file is flushed to the server and not held on
286 the client. When a file is opened the client sends a request to the server to
287 validate the client's local caches. This behavior ensures a file's consistency
288 across multiple NFS clients. When \fB-nocto\fR is in effect, the client does
289 not perform the flush on close and the request for validation, allowing the
290 possiblity of differences among copies of the same file as stored on multiple
291 clients.
292 .sp
293 This option can be used where it can be guaranteed that accesses to a specified
294 file system are made from only one client and only that client. Under such a
295 condition, the effect of \fB-nocto\fR can be a slight performance gain.
296 .RE
297
298 .sp
299 .ne 2
300 .na
301 \fB\fBport=\fR\fIn\fR\fR
302 .ad
303 .sp .6
304 .RS 4n
305 The server \fBIP\fR port number. The default is \fBNFS_PORT\fR. If the
306 \fBport\fR option is specified, and if the resource includes one or more
307 \fBNFS\fR \fBURL\fRs, and if any of the \fBURL\fRs include a \fBport\fR number,
308 then the \fBport\fR number in the option and in the \fBURL\fR must be the same.
309 .RE
310
311 .sp
312 .ne 2
313 .na
314 \fB\fBposix\fR\fR
315 .ad
316 .sp .6
317 .RS 4n
318 Request \fBPOSIX.1\fR semantics for the file system. Requires a mount Version 2
319 \fBmountd\fR(1M) on the server. See \fBstandards\fR(5) for information
320 regarding POSIX.
321 .RE
322
323 .sp
324 .ne 2
325 .na
326 \fB\fBproto=\fR\fInetid\fR | \fBrdma\fR\fR
327 .ad
328 .sp .6
329 .RS 4n
330 By default, the transport protocol that the NFS mount uses is the first
331 available RDMA transport supported both by the client and the server. If no
332 RDMA transport is found, then it attempts to use a TCP transport or, failing
333 that, a UDP transport, as ordered in the \fB/etc/netconfig\fR file. If it does
334 not find a connection oriented transport, it uses the first available
335 connectionless transport.
336 .sp
337 Use this option to override the default behavior.
338 .sp
339 \fBproto\fR is set to the value of \fInetid\fR or \fBrdma\fR. \fInetid\fR is
340 the value of the \fBnetwork_id\fR field entry in the \fB/etc/netconfig\fR file.
341 .sp
342 The UDP protocol is not supported for NFS Version 4. If you specify a UDP
343 protocol with the \fBproto\fR option, NFS version 4 is not used.
344 .RE
345
346 .sp
347 .ne 2
348 .na
349 \fB\fBpublic\fR\fR
350 .ad
351 .sp .6
352 .RS 4n
353 The \fBpublic\fR option forces the use of the public file handle when
354 connecting to the \fBNFS\fR server. The resource specified might not have an
355 \fBNFS\fR \fBURL\fR. See the discussion of \fBURL\fRs and the public option
356 under \fBNFS FILE SYSTEMS\fR for a more detailed discussion.
357 .RE
358
359 .sp
360 .ne 2
361 .na
362 \fB\fBquota\fR | \fBnoquota\fR\fR
363 .ad
364 .sp .6
365 .RS 4n
366 Enable or prevent \fBquota\fR(1M) to check whether the user is over quota on
367 this file system; if the file system has quotas enabled on the server, quotas
368 are still checked for operations on this file system.
369 .RE
370
371 .sp
372 .ne 2
373 .na
374 \fB\fBremount\fR\fR
375 .ad
376 .sp .6
377 .RS 4n
378 Remounts a read-only file system as read-write (using the \fBrw\fR option).
379 This option cannot be used with other \fB-o\fR options, and this option works
380 only on currently mounted read-only file systems.
381 .RE
382
383 .sp
384 .ne 2
385 .na
386 \fB\fBretrans=\fR\fIn\fR\fR
387 .ad
388 .sp .6
389 .RS 4n
390 Set the number of \fBNFS\fR retransmissions to \fIn\fR. The default value is
391 \fB5\fR. For connection-oriented transports, this option has no effect because
392 it is assumed that the transport performs retransmissions on behalf of NFS.
393 .RE
394
395 .sp
396 .ne 2
397 .na
398 \fB\fBretry=\fR\fIn\fR\fR
399 .ad
400 .sp .6
401 .RS 4n
402 The number of times to retry the \fBmount\fR operation. The default for the
403 \fBmount\fR command is \fB10000\fR.
404 .sp
405 The default for the automounter is \fB0\fR, in other words, do not retry. You
406 might find it useful to increase this value on heavily loaded servers, where
407 automounter traffic is dropped, causing unnecessary server not responding
408 errors.
409 .RE
410
411 .sp
412 .ne 2
413 .na
414 \fB\fBrsize=\fR\fIn\fR\fR
415 .ad
416 .sp .6
417 .RS 4n
418 Set the read buffer size to a maximum of \fIn\fR bytes. The default value is
419 \fB1048576\fR when using connection-orientated transports with Version 3 or
420 Version 4 of the \fBNFS\fR protocol, and \fB32768\fR when using connection-less
421 transports. The default can be negotiated down if the server prefers a smaller
422 transfer size. "\fBRead\fR" operations may not necessarily use the maximum
423 buffer size. When using Version 2, the default value is \fB32768\fR for all
424 transports.
425 .RE
426
427 .sp
428 .ne 2
429 .na
430 \fB\fBsec=\fR\fImode\fR\fR
431 .ad
432 .sp .6
433 .RS 4n
434 Set the security \fImode\fR for \fBNFS\fR transactions. If \fBsec=\fR is not
435 specified, then the default action is to use \fBAUTH_SYS\fR over \fBNFS\fR
436 Version 2 mounts, use a user-configured default \fBauth\fR over NFS version 3
437 mounts, or to negotiate a mode over Version 4 mounts.
438 .sp
439 The preferred mode for NFS Version 3 mounts is the default mode specified in
440 \fB/etc/nfssec.conf\fR (see \fBnfssec.conf\fR(4)) on the client. If there is no
441 default configured in this file or if the server does not export using the
442 client's default mode, then the client picks the first mode that it supports in
443 the array of modes returned by the server. These alternatives are limited to
444 the security flavors listed in \fB/etc/nfssec.conf\fR.
445 .sp
446 NFS Version 4 mounts negotiate a security mode when the server returns an array
447 of security modes. The client attempts the mount with each security mode, in
448 order, until one is successful.
449 .sp
450 Only one mode can be specified with the \fBsec=\fR option. See \fBnfssec\fR(5)
451 for the available \fImode\fR options.
452 .RE
453
454 .sp
455 .ne 2
456 .na
457 \fB\fBsecure\fR\fR
458 .ad
459 .sp .6
460 .RS 4n
461 This option has been deprecated in favor of the \fBsec=\fR\fIdh\fR option.
462 .RE
463
464 .sp
465 .ne 2
466 .na
467 \fB\fBtimeo=\fR\fIn\fR\fR
468 .ad
469 .sp .6
470 .RS 4n
471 Set the \fBNFS\fR timeout to \fIn\fR tenths of a second. The default value is
472 \fB11\fR tenths of a second for connectionless transports, and \fB600\fR tenths
473 of a second for connection-oriented transports. This value is ignored for
474 connectionless transports. Such transports might implement their own timeouts,
475 which are outside the control of NFS.
476 .RE
477
478 .sp
479 .ne 2
480 .na
481 \fB\fBvers=\fR\fINFS version number\fR\fR
482 .ad
483 .sp .6
484 .RS 4n
485 By default, the version of \fBNFS\fR protocol used between the client and the
486 server is the highest one available on both systems. The default maximum for
487 the client is Version 4. This can be changed by setting the
488 \fBNFS_CLIENT_VERSMAX\fR parameter in \fB/etc/default/nfs\fR to a valid version
489 (2, 3, or 4). If the \fBNFS\fR server does not support the client's default
490 maximum, the next lowest version attempted until a matching version is found.
491 .RE
492
493 .sp
494 .ne 2
495 .na
496 \fB\fBwsize=\fR\fIn\fR\fR
497 .ad
498 .sp .6
499 .RS 4n
500 Set the write buffer size to a maximum of \fIn\fR bytes. The default value is
501 \fB1048576\fR when using connection-orientated transports with Version 3 or
502 Version 4 of the \fBNFS\fR protocol, and \fB32768\fR when using connection-less
503 transports. The default can be negotiated down if the server prefers a smaller
504 transfer size. "\fBWrite\fR" operations may not necessarily use the maximum
505 buffer size. When using Version 2, the default value is \fB32768\fR for all
506 transports.
507 .RE
508
509 .sp
510 .ne 2
511 .na
512 \fB\fBxattr\fR | \fBnoxattr\fR\fR
513 .ad
514 .sp .6
515 .RS 4n
516 Allow or disallow the creation and manipulation of extended attributes. The
517 default is \fBxattr\fR. See \fBfsattr\fR(5) for a description of extended
518 attributes.
519 .RE
520
521 .RE
522
523 .sp
524 .ne 2
525 .na
526 \fB\fB-O\fR\fR
527 .ad
528 .sp .6
529 .RS 4n
530 Overlay mount. Allow the file system to be mounted over an existing mount
531 point, making the underlying file system inaccessible. If a mount is attempted
532 on a pre-existing mount point without setting this flag, the mount fails,
533 producing the error "device busy."
534 .RE
535
536 .SH NFS FILE SYSTEMS
537 .sp
538 .ne 2
539 .na
540 \fBBackground versus Foreground\fR
541 .ad
542 .sp .6
543 .RS 4n
544 File systems mounted with the \fBbg\fR option indicate that \fBmount\fR is to
545 retry in the background if the server's mount daemon (\fBmountd\fR(1M)) does
546 not respond. \fBmount\fR retries the request up to the count specified in the
547 \fBretry=\fR\fIn\fR option. (Note that the default value for \fBretry\fR
548 differs between \fBmount\fR and \fBautomount\fR. See the description of
549 \fBretry\fR, above.) Once the file system is mounted, each \fBNFS\fR request
550 made in the kernel waits \fBtimeo=\fR\fIn\fR tenths of a second for a response.
551 If no response arrives, the time-out is multiplied by \fB2\fR and the request
552 is retransmitted. When the number of retransmissions has reached the number
553 specified in the \fBretrans=\fR\fIn\fR option, a file system mounted with the
554 \fBsoft\fR option returns an error on the request; one mounted with the
555 \fBhard\fR option prints a warning message and continues to retry the request.
556 .RE
557
558 .sp
559 .ne 2
560 .na
561 \fBHard versus Soft\fR
562 .ad
563 .sp .6
564 .RS 4n
565 File systems that are mounted read-write or that contain executable files
566 should always be mounted with the \fBhard\fR option. Applications using
567 \fBsoft\fR mounted file systems can incur unexpected \fBI/O\fR errors, file
568 corruption, and unexpected program core dumps. The soft option is not
569 recommended.
570 .RE
571
572 .sp
573 .ne 2
574 .na
575 \fBAuthenticated requests\fR
576 .ad
577 .sp .6
578 .RS 4n
579 The server can require authenticated \fBNFS\fR requests from the client.
580 \fBsec=\fR\fIdh\fR authentication might be required. See \fBnfssec\fR(5).
581 .RE
582
583 .sp
584 .ne 2
585 .na
586 \fBURLs and the public option\fR
587 .ad
588 .sp .6
589 .RS 4n
590 If the \fBpublic\fR option is specified, or if the \fIresource\fR includes and
591 \fBNFS\fR \fBURL\fR, \fBmount\fR attempts to connect to the server using the
592 public file handle lookup protocol. See \fIWebNFS Client Specification\fR, RFC
593 2054. If the server supports the public file handle, the attempt is successful;
594 \fBmount\fR does not need to contact the server's \fBrpcbind\fR(1M) and the
595 \fBmountd\fR(1M) daemons to get the port number of the \fBmount\fR server and
596 the initial file handle of \fIpathname\fR, respectively. If the \fBNFS\fR
597 client and server are separated by a firewall that allows all outbound
598 connections through specific ports, such as \fBNFS_PORT\fR, then this enables
599 \fBNFS\fR operations through the firewall. The public option and the \fBNFS\fR
600 \fBURL\fR can be specified independently or together. They interact as
601 specified in the following matrix:
602 .sp
603 .in +2
604 .nf
605 Resource Style
606
607 \fIhost\fR:\fIpathname\fR NFS URL
608
609 public option Force public file Force public file
610 handle and fail handle and fail
611 mount if not supported. mount if not supported.
612
613 Use Native paths. Use Canonical paths.
614
615 default Use MOUNT protocol. Try public file handle
616 with Canonical paths.
617 Fall back to MOUNT
618 protocol if not
619 supported.
620 .fi
621 .in -2
622
623 A Native path is a path name that is interpreted according to conventions used
624 on the native operating system of the \fBNFS\fR server. A Canonical path is a
625 path name that is interpreted according to the \fBURL\fR rules. See \fIUniform
626 Resource Locators (URL)\fR, RFC 1738. See for uses of Native and Canonical
627 paths.
628 .RE
629
630 .sp
631 .ne 2
632 .na
633 \fBReplicated file systems and failover\fR
634 .ad
635 .sp .6
636 .RS 4n
637 \fIresource\fR can list multiple read\(mionly file systems to be used to
638 provide data. These file systems should contain equivalent directory structures
639 and identical files. It is also recommended that they be created by a utility
640 such as \fBrdist\fR(1). The file systems can be specified either with a
641 comma\(miseparated list of \fIhost:/pathname\fR entries and/or \fBNFS\fR
642 \fBURL\fR entries, or with a comma \(miseparated list of hosts, if all file
643 system names are the same. If multiple file systems are named and the first
644 server in the list is down, failover uses the next alternate server to access
645 files. If the read\(mionly option is not chosen, replication is disabled. File
646 access, for NFS Versions 2 and 3, is blocked on the original if NFS locks are
647 active for that file.
648 .RE
649
650 .SS "File Attributes"
651 .sp
652 .LP
653 To improve \fBNFS\fR read performance, files and file attributes are cached.
654 File modification times get updated whenever a write occurs. However, file
655 access times can be temporarily out-of-date until the cache gets refreshed.
656 .sp
657 .LP
658 The attribute cache retains file attributes on the client. Attributes for a
659 file are assigned a time to be flushed. If the file is modified before the
660 flush time, then the flush time is extended by the time since the last
661 modification (under the assumption that files that changed recently are likely
662 to change soon). There is a minimum and maximum flush time extension for
663 regular files and for directories. Setting \fBactimeo=\fR\fIn\fR sets flush
664 time to \fIn\fR seconds for both regular files and directories.
665 .sp
666 .LP
667 Setting \fBactimeo=0\fR disables attribute caching on the client. This means
668 that every reference to attributes is satisfied directly from the server though
669 file data is still cached. While this guarantees that the client always has the
670 latest file attributes from the server, it has an adverse effect on performance
671 through additional latency, network load, and server load.
672 .sp
673 .LP
674 Setting the \fBnoac\fR option also disables attribute caching, but has the
675 further effect of disabling client write caching. While this guarantees that
676 data written by an application is written directly to a server, where it can be
677 viewed immediately by other clients, it has a significant adverse effect on
678 client write performance. Data written into memory-mapped file pages
679 (\fBmmap\fR(2)) are not written directly to this server.
680 .SS "Specifying Values for Attribute Cache Duration Options"
681 .sp
682 .LP
683 The attribute cache duration options are \fBacdirmax\fR, \fBacdirmin\fR,
684 \fBacregmax\fR, \fBacregmin\fR, and \fBactimeo\fR, as described under OPTIONS.
685 A value specified for \fBactimeo\fR sets the values of all attribute cache
686 duration options except for any of these options specified following
687 \fBactimeo\fR on a \fBmount\fR command line. For example, consider the
688 following command:
689 .sp
690 .in +2
691 .nf
692 example# mount -o acdirmax=10,actimeo=1000 server:/path /localpath
693 .fi
694 .in -2
695
696 .sp
697 .LP
698 Because \fBactimeo\fR is the last duration option in the command line, its
699 value (\fB1000\fR) becomes the setting for all of the duration options,
700 including \fBacdirmax\fR. Now consider:
701 .sp
702 .in +2
703 .nf
704 example# mount -o actimeo=1000,acdirmax=10 server:/path /localpath
705 .fi
706 .in -2
707
708 .sp
709 .LP
710 Because the \fBacdirmax\fR option follows \fBactimeo\fR on the command line, it
711 is assigned the value specified (\fB10\fR). The remaining duration options are
712 set to the value of \fBactimeo\fR (\fB1000\fR).
713 .SH EXAMPLES
714 .LP
715 \fBExample 1 \fRMounting an \fBNFS\fR File System
716 .sp
717 .LP
718 To mount an \fBNFS\fR file system:
719
720 .sp
721 .in +2
722 .nf
723 example# mount serv:/usr/src /usr/src
724 .fi
725 .in -2
726 .sp
727
728 .LP
729 \fBExample 2 \fRMounting An \fBNFS\fR File System Read-Only With No suid
730 Privileges
731 .sp
732 .LP
733 To mount an \fBNFS\fR file system read-only with no suid privileges:
734
735 .sp
736 .in +2
737 .nf
738 example# mount -r -o nosuid serv:/usr/src /usr/src
739 .fi
740 .in -2
741 .sp
742
743 .LP
744 \fBExample 3 \fRMounting An \fBNFS\fR File System Over Version 2, with the UDP
745 Transport
746 .sp
747 .LP
748 To mount an \fBNFS\fR file system over Version 2, with the UDP transport:
749
750 .sp
751 .in +2
752 .nf
753 example# mount -o vers=2,proto=udp serv:/usr/src /usr/src
754 .fi
755 .in -2
756 .sp
757
758 .LP
759 \fBExample 4 \fRMounting an \fBNFS\fR File System Using An \fBNFS\fR \fBURL\fR
760 .sp
761 .LP
762 To mount an \fBNFS\fR file system using an \fBNFS\fR \fBURL\fR (a canonical
763 path):
764
765 .sp
766 .in +2
767 .nf
768 example# mount nfs://serv/usr/man /usr/man
769 .fi
770 .in -2
771 .sp
772
773 .LP
774 \fBExample 5 \fRMounting An \fBNFS\fR File System Forcing Use Of The Public
775 File Handle
776 .sp
777 .LP
778 To mount an \fBNFS\fR file system and force the use of the public file handle
779 and an \fBNFS\fR \fBURL\fR (a canonical path) that has a non 7-bit ASCII escape
780 sequence:
781
782 .sp
783 .in +2
784 .nf
785 example# mount -o public nfs://serv/usr/%A0abc /mnt/test
786 .fi
787 .in -2
788 .sp
789
790 .LP
791 \fBExample 6 \fRMounting an \fBNFS\fR File System Using a Native Path
792 .sp
793 .LP
794 To mount an \fBNFS\fR file system using a native path (where the server uses
795 colons (":") as the component separator) and the public file handle:
796
797 .sp
798 .in +2
799 .nf
800 example# mount -o public serv:C:doc:new /usr/doc
801 .fi
802 .in -2
803 .sp
804
805 .LP
806 \fBExample 7 \fRMounting a Replicated Set of \fBNFS\fR File Systems with the
807 Same Pathnames
808 .sp
809 .LP
810 To mount a replicated set of \fBNFS\fR file systems with the same pathnames:
811
812 .sp
813 .in +2
814 .nf
815 example# mount serv\(mia,serv\(mib,serv\(mic:/usr/man /usr/man
816 .fi
817 .in -2
818 .sp
819
820 .LP
821 \fBExample 8 \fRMounting a Replicated Set of \fBNFS\fR File Systems with
822 Different Pathnames
823 .sp
824 .LP
825 To mount a replicated set of \fBNFS\fR file systems with different pathnames:
826
827 .sp
828 .in +2
829 .nf
830 example# mount serv\(mix:/usr/man,serv\(miy:/var/man,nfs://serv-z/man /usr/man
831 .fi
832 .in -2
833 .sp
834
835 .SH FILES
836 .sp
837 .ne 2
838 .na
839 \fB\fB/etc/mnttab\fR\fR
840 .ad
841 .sp .6
842 .RS 4n
843 table of mounted file systems
844 .RE
845
846 .sp
847 .ne 2
848 .na
849 \fB\fB/etc/dfs/fstypes\fR\fR
850 .ad
851 .sp .6
852 .RS 4n
853 default distributed file system type
854 .RE
855
856 .sp
857 .ne 2
858 .na
859 \fB\fB/etc/vfstab\fR\fR
860 .ad
861 .sp .6
862 .RS 4n
863 table of automatically mounted resources
864 .RE
865
866 .SH SEE ALSO
867 .sp
868 .LP
869 \fBrdist\fR(1), \fBlockd\fR(1M), \fBmountall\fR(1M), \fBmountd\fR(1M),
870 \fBnfsd\fR(1M), \fBquota\fR(1M), \fBstatd\fR(1M), \fBmkdir\fR(2),
871 \fBmmap\fR(2), \fBmount\fR(2), \fBopen\fR(2), \fBumount\fR(2), \fBmnttab\fR(4),
872 \fBnfs\fR(4), \fBnfssec.conf\fR(4), \fBattributes\fR(5), \fBfsattr\fR(5),
873 \fBnfssec\fR(5), \fBstandards\fR(5), \fBinet\fR(7P), \fBinet6\fR(7P),
874 \fBlofs\fR(7FS)
875 .sp
876 .LP
877 Callaghan, Brent, \fIWebNFS Client Specification\fR, RFC 2054, October 1996.
878 .sp
879 .LP
880 Callaghan, Brent, \fINFS URL Scheme\fR, RFC 2224, October 1997.
881 .sp
882 .LP
883 Berners-Lee, Masinter & McCahill , \fIUniform Resource Locators (URL)\fR, RFC
884 1738, December 1994.
885 .SH NOTES
886 .sp
887 .LP
888 An \fBNFS\fR server should not attempt to mount its own file systems. See
889 \fBlofs\fR(7FS).
890 .sp
891 .LP
892 If the directory on which a file system is to be mounted is a symbolic link,
893 the file system is mounted on \fBthe directory to which the symbolic link
894 refers,\fR rather than being mounted on top of the symbolic link itself.
895 .sp
896 .LP
897 SunOS 4.x used the \fBbiod\fR maintenance procedure to perform parallel
898 read-ahead and write-behind on \fBNFS\fR clients. SunOS 5.x made \fBbiod\fR
899 obsolete with multi-threaded processing, which transparently performs parallel
900 read-ahead and write-behind.
901 .sp
902 .LP
903 Since the root \fB(\fR/\fB)\fR file system is mounted read-only by the kernel
904 during the boot process, only the \fBremount\fR option (and options that can be
905 used in conjunction with \fBremount\fR) affect the root (\fB/\fR) entry in the
906 \fB/etc/vfstab\fR file.
907 .sp
908 .LP
909 \fBmount_cachefs\fR cannot be used with replicated NFS mounts or any NFS
910 Version 4 mount.
911 .sp
912 .LP
913 The NFS client service is managed by the service management facility,
914 \fBsmf\fR(5), under the service identifier:
915 .sp
916 .in +2
917 .nf
918 svc:/network/nfs/client:default
919 .fi
920 .in -2
921 .sp
922
923 .sp
924 .LP
925 Administrative actions on this service, such as enabling, disabling, or
926 requesting restart, can be performed using \fBsvcadm\fR(1M). The service's
927 status can be queried using the \fBsvcs\fR(1) command.