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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONFIGURATION FILE | NOTES | FILES | SEE ALSO | AUTHORS | COLOPHON |
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NFSDCLD(8) NFSDCLD(8)
nfsdcld - NFSv4 Client Tracking Daemon
nfsdcld [-d] [-F] [-p path] [-s stable storage dir]
nfsdcld is the NFSv4 client tracking daemon. It is not necessary
to run this daemon on machines that are not acting as NFSv4
servers.
When a network partition is combined with a server reboot, there
are edge conditions that can cause the server to grant lock
reclaims when other clients have taken conflicting locks in the
interim. A more detailed explanation of this issue is described in
RFC 3530, section 8.6.3.
In order to prevent these problems, the server must track a small
amount of per-client information on stable storage. This daemon
provides the userspace piece of that functionality.
-d, --debug
Enable debug level logging.
-F, --foreground
Runs the daemon in the foreground and prints all output to
stderr
-p path, --pipefsdir=path
Location of the rpc_pipefs filesystem. The default value is
/var/lib/nfs/rpc_pipefs.
-s storage_dir, --storagedir=storage_dir
Directory where stable storage information should be kept. The
default value is /var/lib/nfs/nfsdcld.
The following values are recognized in the [nfsdcld] section of
the /etc/nfs.conf configuration file:
storagedir
Equivalent to -s/--storagedir.
debug
Setting "debug = 1" is equivalent to -d/--debug.
In addition, the following value is recognized from the [general]
section:
pipefs-directory
Equivalent to -p/--pipefsdir.
The Linux kernel NFSv4 server has historically tracked this
information on stable storage by manipulating information on the
filesystem directly, in the directory to which
/proc/fs/nfsd/nfsv4recoverydir points.
This changed with the original introduction of nfsdcld upcall in
kernel version 3.4, which was later deprecated in favor of the
nfsdcltrack(8) usermodehelper program, support for which was added
in kernel version 3.8. However, since the usermodehelper upcall
does not work in containers, support for a new version of the
nfsdcld upcall was added in kernel version 5.2.
This daemon requires a kernel that supports the nfsdcld upcall. On
older kernels, if the legacy client name tracking code was in use,
then the kernel would not create the pipe that nfsdcld uses to
talk to the kernel. On newer kernels, nfsd attempts to initialize
client tracking in the following order: First, the nfsdcld
upcall. Second, the nfsdcltrack usermodehelper upcall. Finally,
the legacy client tracking.
This daemon should be run as root, as the pipe that it uses to
communicate with the kernel is only accessible by root. The daemon
however does drop all superuser capabilities after starting.
Because of this, the storagedir should be owned by root, and be
readable and writable by owner.
The daemon now supports different upcall versions to allow the
kernel to pass additional data to be stored in the on-disk
database. The kernel will query the supported upcall version from
nfsdcld during client tracking initialization. A restart of nfsd
is not necessary after upgrading nfsdcld, however nfsd will not
use a later upcall version until restart. A restart of nfsd is
necessary after downgrading nfsdcld, to ensure that nfsd does not
use an upcall version that nfsdcld does not support.
Additionally, a downgrade of nfsdcld requires the schema of the
on-disk database to be downgraded as well. That can be
accomplished using the nfsdclddb(8) utility.
/var/lib/nfs/nfsdcld/main.sqlite
nfsdcltrack(8), nfsdclddb(8)
The nfsdcld daemon was developed by Jeff Layton
<jlayton@redhat.com> with modifications from Scott Mayhew
<smayhew@redhat.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
⟨git://git.linux-nfs.org/projects/steved/nfs-utils.git⟩ on
2025-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2025-01-25.) 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
2011-12-21 NFSDCLD(8)
Pages that refer to this page: nfsdclddb(8)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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