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NFSREF(8) System Manager's Manual NFSREF(8)
nfsref - manage NFS referrals
nfsref [-?d] [-t type] add pathname server export [ server export
... ]
nfsref [-?d] [-t type] remove pathname
nfsref [-?d] [-t type] lookup pathname
NFS version 4 introduces the concept of file system referrals to
NFS. A file system referral is like a symbolic link on a file
server to another file system share, possibly on another file
server. On an NFS client, a referral behaves like an automounted
directory. The client, under the server's direction, mounts a
new NFS export automatically when an application first accesses
that directory.
Referrals are typically used to construct a single file name
space across multiple file servers. Because file servers control
the shape of the name space, no client configuration is required,
and all clients see the same referral information.
The Linux NFS server supports NFS version 4 referrals.
Administrators can specify the refer= export option in
/etc/exports to configure a list of exports from which the client
can choose. See exports(5) for details.
The nfsref(8) command is a simple way to get started managing
junction metadata. Other administrative commands provide richer
access to junction information.
Subcommands
Valid nfsref(8) subcommands are:
add Adds junction information to the directory named by
pathname. The named directory must already exist, and
must not already contain junction information. Regular
directory contents are obscured to NFS clients by this
operation.
A list of one or more file server and export path pairs is
also specified on the command line. When creating an NFS
basic junction, this list is stored in an extended
attribute of the directory.
If junction creation is successful, the nfsref(8) command
flushes the kernel's export cache to remove previously
cached junction information.
remove Removes junction information from the directory named by
pathname. The named directory must exist, and must
contain junction information. Regular directory contents
are made visible to NFS clients again by this operation.
If junction deletion is successful, the nfsref(8) command
flushes the kernel's export cache to remove previously
cached junction information.
lookup Displays junction information stored in the directory
named by pathname. The named directory must exist, and
must contain junction information.
When looking up an NFS basic junction, the junction
information in the directory is listed on stdout.
Command line options
-d, --debug
Enables debugging messages during operation.
-t, --type=junction-type
Specifies the junction type for the operation. Valid
values for junction-type are nfs-basic or nfs-fedfs.
For the add subcommand, the default value if this option
is not specified is nfs-basic. For the remove and lookup
subcommands, the --type option is not required. The
nfsref(8) command operates on whatever junction contents
are available.
Suppose you have two file servers, top.example.net and
home.example.net. You want all your clients to mount
top.example.net:/ and then see the files under home.example.net:/
automatically in top:/home.
On top.example.net, you might issue this command as root:
# mkdir /home
# nfsref --type=nfs-basic add /home home.example.net /
Created junction /home.
/etc/exports
NFS server export table
exports(5)
RFC 5661 for a description of NFS version 4 referrals
Chuck Lever <chuck.lever@oracle.com>
This page is part of the nfs-utils (NFS utilities) project.
Information about the project can be found at
⟨http://linux-nfs.org/wiki/index.php/Main_Page⟩. If you have a
bug report for this manual page, see
⟨http://linux-nfs.org/wiki/index.php/Main_Page⟩. This page was
obtained from the project's upstream Git repository
⟨http://git.linux-nfs.org/?p=steved/nfs-utils.git;a=summary⟩ on
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-16.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
9 Jan 2018 NFSREF(8)
Pages that refer to this page: nfsref(8)
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