NAME

       nfsdcld - NFSv4 Client Tracking Daemon

SYNOPSIS

       nfsdcld [-d] [-F] [-p path] [-s stable storage dir]

DESCRIPTION

       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.

OPTIONS

       -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.

CONFIGURATION FILE

       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.

NOTES

       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
       accessable  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.

FILES

       /var/lib/nfs/nfsdcld/main.sqlite

SEE ALSO

       nfsdcltrack(8), nfsdclddb(8)

AUTHORS

       The nfsdcld daemon was developed by Jeff Layton <jlayton@redhat.com> with modifications from Scott Mayhew
       <smayhew@redhat.com>.

                                                   2011-12-21                                         NFSDCLD(8)