NFSDCLTRACK(8)															    NFSDCLTRACK(8)

NAME

       nfsdcltrack - NFSv4 Client Tracking Callout Program

SYNOPSIS

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

DESCRIPTION

       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
       8.6.3.

       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.

OPTIONS

       -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.

COMMANDS

       nfsdcltrack requires a command for each invocation. Supported commands are:

       init
	   Initialize the database. This command requires no argument.

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

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

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

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

LEGACY TRANSITION MECHANISM

       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. If the kernel passes the correct information, then nfsdcltrack
       can use it to allow a seamless transition from the old client tracking scheme to the new one.

       On a check operation, if there is no record of the client in the database, nfsdcltrack will look to see if the NFSDCLTRACK_LEGACY_RECDIR
       environment variable is set. If it is, then it will fetch that value and see if a directory exists by that name. If it does, then the check
       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.

NOTES

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

AUTHORS

       nfsdcltrack was developed by Jeff Layton <jlayton@redhat.com>.

								    2012-10-24							    NFSDCLTRACK(8)