Lockd
Lockd is a daemon that provides record-level locking services in an NFS
environment.
Lockd processes lock requests that are either sent locally by the kernel, or
remotely by another lock daemon. Lockd forwards lock requests for remote data to
the server siteÆs lock daemon through RPC/XDR. Lockd then requests the status monitor daemon, statd, for monitor service. The reply to the lock request will not be sent to the
kernel until the status daemon and the server siteÆs lock daemon have replied.
When a server recovers, it waits for a grace period for all client-site lock
daemons to submit reclaim requests. Client-site lock daemons, on the other hand,
are notified by the status monitor daemon of the server recovery and promptly
resubmits previously granted lock requests. If a lock daemon fails to secure a
previously granted lock at the server site, then it sends SIGLOST to a process.