nfsdcltrack [-d] [-f] [-s stable storage dir] <command> <args...>

       nfsdcltack is the NFSv4 client tracking callout program. It is not
       necessary to install 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

       In order to prevent these problems, the server must track a small
       amount of per-client information on stable storage. This program
       provides the userspace piece of that functionality. When the kernel
       needs to manipulate the database that stores this info, it will execute
       this program to handle it.

       -d, --debug
           Enable debug level logging.

       -f, --foreground
           Log to stderr instead of syslog.

       -s storagedir, --storagedir=storage_dir
           Directory where stable storage information should be kept. The
           default value is /var/lib/nfs/nfsdcltrack.

       nfsdcltrack requires a command for each invocation. Supported commands

           Initialize the database. This command requires no argument.

           Create a new client record (or update the timestamp on an existing
           one). This command requires a hex-encoded nfs_client_id4 as an

           Remove a client record from the database. This command requires a
           hex-encoded nfs_client_id4 as an argument.

           Check to see if a nfs_client_id4 is allowed to reclaim. This
           command requires a hex-encoded nfs_client_id4 as an argument.

           Remove any unreclaimed client records from the database. This
           command requires a epoch boot time as an argument.

       operation will succeed and the directory will be removed.

       On a gracedone operation, nfsdcltrack will look to see if the
       NFSDCLTRACK_LEGACY_TOPDIR environment variable is set. If it is, then
       it will attempt to clean out that directory prior to exiting.

       Note that this transition is one-way. If the machine subsequently
       reboots back into an older kernel that does not support the nfsdcltrack
       upcall then the clients will not be able to recover their state.

       This program requires a kernel that supports the nfsdcltrack
       usermodehelper upcall. This support was first added to mainline kernels
       in 3.8.

       nfsdcltrack was developed by Jeff Layton <>.

                                  2012-10-24                    NFSDCLTRACK(8)
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