Unix‎ > ‎Solaris‎ > ‎Solaris man pages‎ > ‎1m‎ > ‎

mount_nfs


NAME
     mount_nfs - mount remote NFS resources

SYNOPSIS
     mount [-F nfs] [generic_options] [-o specific_options] [-O] resource


     mount [-F nfs] [generic_options] [-o specific_options] [-O] mount_point


     mount [-F nfs] [generic_options] [-o specific_options]
          [-O] resource mount_point


DESCRIPTION
     The mount utility attaches a named resource to the file sys-
     tem  hierarchy  at  the pathname location mount_point, which
     must already exist. If mount_point has any contents prior to
     the  mount  operation,  the contents remain hidden until the
     resource is once again unmounted.


     mount_nfs starts the lockd(1M) and statd(1M) daemons if they
     are not already running.


     If the resource is listed in the /etc/vfstab file, the  com-
     mand  line  can  specify either resource or mount_point, and
     mount consults /etc/vfstab for more information. If  the  -F
     option  is  omitted,  mount  takes the file system type from
     /etc/vfstab.


     If the resource is not listed in the /etc/vfstab file,  then
     the  command  line  must  specify  both the resource and the
     mount_point.


     host can  be  an  IPv4  or  IPv6  address  string.  As  IPv6
     addresses  already contain colons, enclose host in a pair of
     square brackets when specifying an IPv6 address string. Oth-
     erwise the first occurrence of a colon can be interpreted as
     the separator between the host name and path,  for  example,
     [1080::8:800:200C:417A]:tmp/file.     See    inet(7P)    and
     inet6(7P).

     host:pathname

         Where host is the name of the NFS server host, and path-
         name  is  the  path  name of the directory on the server
         being mounted. The path name is interpreted according to
         the   server's  path  name  parsing  rules  and  is  not
         necessarily slash-separated,  though  on  most  servers,
         this is the case.


     nfs://host[:port]/pathname

         This is an NFS URL and follows the  standard  convention
         for  NFS  URLs as described in NFS URL Scheme, RFC 2224.
         See the discussion of URL's and the public option  under
         NFS FILE SYSTEMS for a more detailed discussion.


     host:pathname nfs://host[:port]/pathname


         host:pathname   is    a    comma-separated    list    of
         host:pathname.

         See the discussion of replicated file systems and  fail-
         over  under NFS FILE SYSTEMS for a more detailed discus-
         sion.


     hostlist pathname

         hostlist is a comma-separated list of hosts.

         See the discussion of replicated file systems and  fail-
         over  under NFS FILE SYSTEMS for a more detailed discus-
         sion.



     The mount command maintains a table of mounted file  systems
     in /etc/mnttab, described in mnttab(4).


     mount_nfs supports both NFSv3 and NFSv4 mounts. The  default
     NFS version is NFSv4.

OPTIONS
     See mount(1M) for the list of supported generic_options. See
     share_nfs(1M) for a description of server options.

     -o specific_options

         Set file system specific options according to  a  comma-
         separated list with no intervening spaces.

         acdirmax=n

             Hold cached attributes for no more  than  n  seconds
             after directory update. The default value is 60.


         acdirmin=n

             Hold cached attributes for at least n seconds  after
             directory update. The default value is 30.


         acregmax=n

             Hold cached attributes for no more  than  n  seconds
             after file modification. The default value is 60.


         acregmin=n

             Hold cached attributes for at least n seconds  after
             file modification. The default value is 3.


         actimeo=n

             Set min and max times for regular files  and  direc-
             tories  to  n seconds. See "File Attributes," below,
             for a description of  the  effect  of  setting  this
             option to 0.

             See "Specifying Values for Attribute Cache  Duration
             Options,"  below, for a description of how acdirmax,
             acdirmin, acregmax, acregmin, and actimeo are parsed
             on a mount command line.


         bg | fg

             If the first attempt fails, retry in the background,
             or, in the foreground. The default is fg.


         forcedirectio | noforcedirectio

             If forcedirectio is specified, then for the duration
             of  the  mount,  forced  direct  I/O is used. If the
             filesystem is mounted using forcedirectio,  data  is
             transferred directly between client and server, with
             no buffering on the client.  If  the  filesystem  is
             mounted  using  noforcedirectio, data is buffered on
             the client. forcedirectio is  a  performance  option
             that  is  of  benefit  only in large sequential data
             transfers. The default behavior is noforcedirectio.

         grpid

             By default, the GID associated with a newly  created
             file  obeys the System V semantics; that is, the GID
             is set to the effective GID of the calling  process.
             This  behavior  can be overridden on a per-directory
             basis by setting  the  set-GID  bit  of  the  parent
             directory;  in this case, the GID of a newly created
             file is set to the GID of the parent directory  (see
             open(2) and mkdir(2)). Files created on file systems
             that are mounted with the  grpid  option  obeys  BSD
             semantics  independent of whether the set-GID bit of
             the parent directory is set; that  is,  the  GID  is
             unconditionally  inherited  from  that of the parent
             directory.


         hard | soft

             Continue to retry requests until the server responds
             (hard)  or  give  up and return an error (soft). The
             default value is hard. Note that  NFSv4  clients  do
             not support soft mounts.


         intr | nointr

             Allow (do not allow) keyboard interrupts to  kill  a
             process that is hung while waiting for a response on
             a hard-mounted file system.  The  default  is  intr,
             which  makes  it  possible  for clients to interrupt
             applications that can be waiting for a remote mount.


         noac

             Suppress data and attribute caching. The data  cach-
             ing  that  is  suppressed  is  the write-behind. The
             local page  cache  is  still  maintained,  but  data
             copied into it is immediately written to the server.


         nocto

             Do not perform the normal close-to-open consistency.
             When  a file is closed, all modified data associated
             with the file is flushed to the server and not  held
             on  the  client.  When  a  file is opened the client
             sends a  request  to  the  server  to  validate  the
             client's  local  caches.  This  behavior  ensures  a
             file's consistency across multiple NFS clients. When
             -nocto is in effect, the client does not perform the
             flush on  close  and  the  request  for  validation,
             allowing  the possiblity of differences among copies
             of the same file as stored on multiple clients.

             This option can be used where it can  be  guaranteed
             that  accesses  to  a specified file system are made
             from only one client and  only  that  client.  Under
             such  a  condition,  the  effect  of -nocto can be a
             slight performance gain.


         port=n

             The server IP port number. The default is  NFS_PORT.
             If the port option is specified, and if the resource
             includes one or more NFS URLs, and  if  any  of  the
             URLs  include a port number, then the port number in
             the option and in the URL must be the same.


         posix

             Request  POSIX.1  semantics  for  the  file  system.
             Requires a mount Version 2 mountd(1M) on the server.
             See standards(5) for information regarding POSIX.


         proto=netid | rdma

             By default, the  transport  protocol  that  the  NFS
             mount uses is the first available TCP transport sup-
             ported both by the client and the server. If no  TCP
             transport  is  found,  then it attempts to use a UDP
             transport, as ordered in the /etc/netconfig file.

             Use this option to override the default behavior.

             proto is set to the value of netid or rdma. netid is
             the  value  of  the  network_id  field  entry in the
             /etc/netconfig file.

             The UDP protocol is not supported for NFS Version 4.
             If you specify a UDP protocol with the proto option,
             NFS version 4 is not used.


         public

             The public option forces the use of the public  file
             handle  when  connecting  to  the  NFS  server.  The
             resource specified might not have an  NFS  URL.  See
             the  discussion  of URLs and the public option under
             NFS FILE SYSTEMS for a more detailed discussion.


         quota | noquota

             Enable or prevent quota(1M)  to  check  whether  the
             user  is over quota on this file system; if the file
             system has quotas enabled on the server, quotas  are
             still checked for operations on this file system.


         remount

             Remounts  a  read-only  file  system  as  read-write
             (using  the  rw  option). This option cannot be used
             with other -o options, and this option works only on
             currently mounted read-only file systems.


         retrans=n

             Set the number of  NFS  retransmissions  to  n.  The
             default  value  is  5. For connection-oriented tran-
             sports, this option has  no  effect  because  it  is
             assumed  that the transport performs retransmissions
             on behalf of NFS.


         retry=n

             The number of times to retry  the  mount  operation.
             The default for the mount command is 10000.

             The default for  the  automounter  is  0,  in  other
             words,  do  not  retry.  You might find it useful to
             increase this value on heavily loaded servers, where
             automounter  traffic is dropped, causing unnecessary
             server not responding errors.


         rsize=n

             Set the read buffer size to a maximum  of  n  bytes.
             The  default value is 1048576 when using connection-
             orientated transports with Version 3 or Version 4 of
             the  NFS  protocol, and 32768 when using connection-
             less transports. The default can be negotiated  down
             if  the  server  prefers  a  smaller  transfer size.
             "Read" operations may not necessarily use  the  max-
             imum  buffer size. When using Version 2, the default
             value is 32768 for all transports.

         sec=mode

             Set the security mode for NFS transactions. If  sec=
             is  not specified, then the default action is to use
             AUTH_SYS over NFS Version 2 mounts, or to  negotiate
             a mode over NFS Version 3 or Version 4 mounts.

             NFS Version 3 mounts negotiate a security mode  when
             the  server  returns an array of security modes. The
             client picks the first mode in  the  array  that  is
             supported  on  the  client.  In negotiations, an NFS
             Version 3 client is limited to the security  flavors
             listed in /etc/nfssec.conf.

             NFS Version 4 mounts negotiate a security mode  when
             the  server  returns an array of security modes. The
             client attempts the mount with each  security  mode,
             in order, until one is successful.

             Only one mode can be specified with the sec= option.
             See nfssec(5) for the available mode options.


         secure

             This option has been  deprecated  in  favor  of  the
             sec=dh option.


         timeo=n

             Set the NFS timeout to n tenths  of  a  second.  The
             default  value  is 11 tenths of a second for connec-
             tionless transports, and 600 tenths of a second  for
             connection-oriented   transports.   This   value  is
             ignored for connectionless  transports.  Such  tran-
             sports might implement their own timeouts, which are
             outside the control of NFS.


         vers=NFS version number

             By default, the version of NFS protocol used between
             the  client and the server is the highest one avail-
             able on both systems. The default  maximum  for  the
             client  is Version 4. This can be changed by setting
             the NFS_CLIENT_VERSMAX parameter in /etc/default/nfs
             to  a  valid version (2, 3, or 4). If the NFS server
             does not support the client's default  maximum,  the
             next  lowest version attempted until a matching ver-
             sion is found.

         wsize=n

             Set the write buffer size to a maximum of  n  bytes.
             The  default value is 1048576 when using connection-
             orientated transports with Version 3 or Version 4 of
             the  NFS  protocol, and 32768 when using connection-
             less transports. The default can be negotiated  down
             if  the  server  prefers  a  smaller  transfer size.
             "Write" operations may not necessarily use the  max-
             imum  buffer size. When using Version 2, the default
             value is 32768 for all transports.


         xattr | noxattr

             Allow or disallow the creation and  manipulation  of
             extended  attributes.  The  default  is  xattr.  See
             fsattr(5) for a description of extended attributes.



     -O

         Overlay mount. Allow the file system to be mounted  over
         an existing mount point, making the underlying file sys-
         tem inaccessible. If a mount  is  attempted  on  a  pre-
         existing  mount  point  without  setting  this flag, the
         mount fails, producing the error "device busy."


NFS FILE SYSTEMS
     Background versus Foreground

         File systems mounted with the bg  option  indicate  that
         mount  is  to  retry  in  the background if the server's
         mount  daemon  (mountd(1M))  does  not  respond.   mount
         retries  the  request  up  to the count specified in the
         retry=n option. (Note that the default value  for  retry
         differs between mount and automount. See the description
         of retry, above.) Once the file system is mounted,  each
         NFS request made in the kernel waits timeo=n tenths of a
         second for a  response.  If  no  response  arrives,  the
         time-out   is   multiplied  by  2  and  the  request  is
         retransmitted. When the number  of  retransmissions  has
         reached  the number specified in the retrans=n option, a
         file system mounted with  the  soft  option  returns  an
         error  on  the request; one mounted with the hard option
         prints a warning message  and  continues  to  retry  the
         request.



     Hard versus Soft

         File systems that are mounted read-write or that contain
         executable  files should always be mounted with the hard
         option. Applications using soft mounted file systems can
         incur  unexpected I/O errors, file corruption, and unex-
         pected program core dumps. The soft option is not recom-
         mended.


     Authenticated requests

         The server can require authenticated NFS  requests  from
         the client. sec=dh authentication might be required. See
         nfssec(5).


     URLs and the public option

         If the public option is specified, or  if  the  resource
         includes  and  NFS URL, mount attempts to connect to the
         server using the public file handle lookup protocol. See
         WebNFS  Client  Specification,  RFC  2054. If the server
         supports the public file handle, the attempt is success-
         ful;  mount  does  not  need  to  contact  the  server's
         rpcbind(1M) and the mountd(1M) daemons to get  the  port
         number  of  the mount server and the initial file handle
         of pathname, respectively. If the NFS client and  server
         are  separated  by  a  firewall that allows all outbound
         connections through specific ports,  such  as  NFS_PORT,
         then  this  enables NFS operations through the firewall.
         The public option and  the  NFS  URL  can  be  specified
         independently or together. They interact as specified in
         the following matrix:

                              Resource Style

                               host:pathname              NFS URL

           public option      Force public file          Force public file
                               handle and fail            handle and fail
                               mount if not supported.    mount if not supported.

                               Use Native paths.          Use Canonical paths.

           default            Use MOUNT protocol.        Try public file handle
                                                          with Canonical paths.
                                                          Fall back to MOUNT
                                                          protocol if not
                                                          supported.

         A Native  path  is  a  path  name  that  is  interpreted
         according  to  conventions  used on the native operating
         system of the NFS server. A Canonical  path  is  a  path
         name that is interpreted according to the URL rules. See
         Uniform Resource Locators (URL), RFC 1738. See  for uses
         of Native and Canonical paths.


     Replicated file systems and failover

         resource can list multiple read-only file systems to  be
         used  to provide data. These file systems should contain
         equivalent directory structures and identical files.  It
         is  also  recommended  that they be created by a utility
         such as rdist(1). The  file  systems  can  be  specified
         either  with  a  comma-separated  list of host:/pathname
         entries  and/or  NFS  URL  entries,  or  with  a   comma
         -separated  list  of hosts, if all file system names are
         the same. If multiple file systems  are  named  and  the
         first server in the list is down, failover uses the next
         alternate server  to  access  files.  If  the  read-only
         option  is  not  chosen,  replication  is disabled. File
         access, for NFS Versions 2 and 3, is blocked on the ori-
         ginal if NFS locks are active for that file.


  File Attributes
     To improve NFS read performance, files and  file  attributes
     are  cached.  File modification times get updated whenever a
     write occurs. However, file access times can be  temporarily
     out-of-date until the cache gets refreshed.


     The attribute cache retains file attributes on  the  client.
     Attributes  for a file are assigned a time to be flushed. If
     the file is modified before the flush time, then  the  flush
     time  is  extended  by  the time since the last modification
     (under the assumption that files that changed  recently  are
     likely to change soon). There is a minimum and maximum flush
     time extension for regular files and for  directories.  Set-
     ting actimeo=n sets flush time to n seconds for both regular
     files and directories.


     Setting actimeo=0 disables attribute caching on the  client.
     This  means  that every reference to attributes is satisfied
     directly from the server though file data is  still  cached.
     While  this guarantees that the client always has the latest
     file attributes from the server, it has an adverse effect on
     performance  through  additional  latency, network load, and
     server load.


     Setting the noac option also disables attribute caching, but
     has  the  further  effect of disabling client write caching.
     While this guarantees that data written by an application is
     written directly to a server, where it can be viewed immedi-
     ately by other clients, it has a significant adverse  effect
     on client write performance. Data written into memory-mapped
     file pages  (mmap(2))  are  not  written  directly  to  this
     server.

  Specifying Values for Attribute Cache Duration Options
     The attribute cache duration options are acdirmax, acdirmin,
     acregmax, acregmin, and actimeo, as described under OPTIONS.
     A value specified for actimeo sets the values of all  attri-
     bute  cache duration options except for any of these options
     specified following actimeo on a  mount  command  line.  For
     example, consider the following command:

       example# mount -o acdirmax=10,actimeo=1000 server:/path /localpath



     Because actimeo is the last duration option in  the  command
     line,  its  value  (1000) becomes the setting for all of the
     duration options, including acdirmax. Now consider:

       example# mount -o actimeo=1000,acdirmax=10 server:/path /localpath



     Because the acdirmax option follows actimeo on  the  command
     line, it is assigned the value specified (10). The remaining
     duration options are set to the value of actimeo (1000).

EXAMPLES
     Example 1 Mounting an NFS File System


     To mount an NFS file system:


       example# mount serv:/usr/src /usr/src



     Example 2 Mounting An NFS File System Read-Only With No suid
     Privileges


     To  mount  an  NFS  file  system  read-only  with  no   suid
     privileges:


       example# mount -r -o nosuid serv:/usr/src /usr/src



     Example 3 Mounting An NFS File System Over Version  2,  with
     the UDP Transport


     To mount an NFS file system over Version  2,  with  the  UDP
     transport:


       example# mount -o vers=2,proto=udp serv:/usr/src /usr/src



     Example 4 Mounting an NFS File System Using An NFS URL


     To mount an NFS file system using an NFS  URL  (a  canonical
     path):


       example# mount nfs://serv/usr/man /usr/man



     Example 5 Mounting An NFS File System  Forcing  Use  Of  The
     Public File Handle


     To mount an NFS file system and force the use of the  public
     file handle and an NFS URL (a canonical path) that has a non
     7-bit ASCII escape sequence:


       example# mount -o public nfs://serv/usr/%A0abc /mnt/test



     Example 6 Mounting an NFS File System Using a Native Path


     To mount an NFS file system using a native path  (where  the
     server uses colons (":") as the component separator) and the
     public file handle:


       example# mount -o public serv:C:doc:new /usr/doc



     Example 7 Mounting a Replicated Set of NFS File Systems with
     the Same Pathnames


     To mount a replicated set of NFS file systems with the  same
     pathnames:


       example# mount serv-a,serv-b,serv-c:/usr/man /usr/man



     Example 8 Mounting a Replicated Set of NFS File Systems with
     Different Pathnames


     To mount a replicated set of NFS file systems with different
     pathnames:


       example# mount serv-x:/usr/man,serv-y:/var/man,nfs://serv-z/man /usr/man



FILES
     /etc/mnttab

         table of mounted file systems


     /etc/dfs/fstypes

         default distributed file system type


     /etc/vfstab

         table of automatically mounted resources


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:









     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWnfscu                   |
    |_____________________________|_____________________________|


SEE ALSO
     rdist(1), lockd(1M), mountall(1M),  mountd(1M),  mountd(1M),
     quota(1M),  statd(1M), mkdir(2), mmap(2), mount(2), open(2),
     umount(2), mnttab(4), attributes(5),  fsattr(5),  nfssec(5),
     standards(5), inet(7P), inet6(7P), lofs(7FS)


     Callaghan, Brent, WebNFS  Client  Specification,  RFC  2054,
     October 1996.


     Callaghan, Brent, NFS URL Scheme, RFC 2224, October 1997.


     Berners-Lee, Masinter & McCahill , Uniform Resource Locators
     (URL), RFC 1738, December 1994.

NOTES
     An NFS server should not attempt to mount its own file  sys-
     tems. See lofs(7FS).


     If the directory on which a file system is to be mounted  is
     a symbolic link, the file system is mounted on the directory
     to which the symbolic link refers, rather than being mounted
     on top of the symbolic link itself.


     SunOS 4.x used the biod  maintenance  procedure  to  perform
     parallel  read-ahead  and write-behind on NFS clients. SunOS
     5.x made biod obsolete with multi-threaded processing, which
     transparently performs parallel read-ahead and write-behind.


     Since the root (/) file system is mounted read-only  by  the
     kernel during the boot process, only the remount option (and
     options that can be used in conjunction with remount) affect
     the root (/) entry in the /etc/vfstab file.


     mount_cachefs cannot be used with replicated NFS  mounts  or
     any NFS Version 4 mount.




Man pages from Solaris 10 Update 8. See docs.sun.com and www.oracle.com for further documentation and Solaris information.
Comments