lockd(1M)

NAME
     lockd - NFS lock daemon

SYNOPSIS
     /usr/etc/rpc.lockd [ -g graceperiod ] [ -l ] [ nservers ]

DESCRIPTION
     lockd provides the inherently stateful locking services within the
     stateless NFS environment. It allows the locking of records and files
     between applications running on different physical machines sharing the
     same file systems mounted with NFS.  Nservers is the number of lockd
     servers to start.

     Locks are presently advisory only. The lock style implemented by lockd is
     that specified in the SVID (see lockf(3C) and fcntl(2)).  There is no
     interaction between the lockd's locks and flock(3B) style locks.

     lockd is started during system initialization if the chkconfig(1M)
     ``lockd'' flag is set on.  Command-line options belong in
     /etc/config/lockd.options.

     If nfsd(1M) is running, lockd will register its RPC services and exit,
     leaving nfsd to handle the requests.

     lockd processes lock requests that are either sent locally by the kernel
     or remotely by another lock daemon.  In the case of local lock requests
     for remote data, lockd forwards the lock requests to the server site's
     lock daemon through the RPC/XDR(3R) package.  lockd then requests the
     local status monitor daemon, statd(1M), for monitor service of the
     server. The reply to the lock request will not be sent to the kernel
     until the status daemon and the server site's lock daemon have replied.

     When a server recovers, it waits for a grace period for all client site
     lockds to submit reclaim requests.  Client site lockds are notified by
     the statd of the server recovery and promptly resubmit previously granted
     lock requests.  If a lockd fails to secure a previously granted lock at
     the server site, it sends SIGUSR1 to the application process.  The
     process must explicitly handle this signal if the loss of a lock should
     cause it to terminate.

OPTIONS
     -g graceperiod
               lockd uses graceperiod (seconds) as the grace period duration
               instead of the default value (see TUNING below).

     -l        Set SVID locks for files which are locked by DOS machines
               running PC-NFS and compatible file sharing utilities.
               Normally, lockd does not set SVID locks for such requests.
TUNING
     Lockd has four tunable parameters:  lockd_grace_period,
     lock_share_requests, nlm_granted_timeout, and nlm_maxdupreqs.
     Lockd_grace_period controls the starup grace period for the reclaiming of
     locks.  This was previously controlled by the -g command line option.
     Lock_share_requests tells lockd to preform UNIX file locking for share
     and unshare requests.  Nlm_granted_timeout controlls the timeout used in
     making NLM_GRANTED and NLMPROC_GRANTED callbacks for blocked lock
     requests which have been granted.  This value is specified in tenths of a
     second.  Nlm_maxdupreqs controlls how many NLM RPC duplicate request
     cache entries are allocated.  The default setting is 0.  This causes the
     allocation to be sized based upon the memory size of the system.

NOTE
     The reply to a lock request for remote data is delayed until all daemons
     become available.

     In the Sun implementation, lockd sends SIGLOST.  when a lock is lost.
     The IRIX implementation sends SIGUSR1.  Programs should establish a
     signal handler to catch this signal and exit.

SEE ALSO
     fcntl(2), signal(2), lockf(3C), statd(1M)