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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
2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2024-05-10.) 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 2024-06-26 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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