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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.