host status monitoring daemon
utility is a daemon which
daemons on other
hosts to provide a status monitoring service. The daemon accepts requests from
programs running on the local host (typically,
the NFS file locking daemon) to monitor the status of specified hosts. If a
monitored host crashes and restarts, the remote daemon will notify the local
daemon, which in turn will notify the local program(s) which requested the
monitoring service. Conversely, if this host crashes and re-starts, when the
re-starts, it will notify all of
the hosts which were being monitored at the time of the crash.
The following option is available:
- Cause debugging information to be written to syslog, recording all RPC
transactions to the daemon. These messages are logged with level LOG_DEBUG
and facility LOG_DAEMON. Error conditions are logged irrespective of this
option, using level LOG_ERR.
- Specify specific IP addresses to bind to. This option may be specified
multiple times. If no
-h option is
rpc.statd will bind to
INADDR_ANY. Note that when specifying
IP addresses with
rpc.statd will automatically add
127.0.0.1 and if IPv6 is enabled,
::1 to the list.
-p option allow to force the daemon
to bind to the specified port, for both
AF_INET and AF_INET6 address families.
utility must NOT be invoked by
because the protocol assumes that the daemon will run from system start time.
Instead, it should be run from
after the network has been started.
- non-volatile record of currently monitored hosts.
- RPC protocol specification used by local applications to register
The implementation is based on the specification in X/Open CAE Specification
C218, "Protocols for X/Open PC Interworking: XNFS, Issue 4", ISBN 1
872630 66 9
There is no means for the daemon to tell when a monitored host has disappeared
permanently (e.g. catastrophic hardware failure), as opposed to transient
failure of the host or an intermediate router. At present, it will re-try
notification attempts at frequent intervals for 10 minutes, then hourly, and
finally gives up after 24 hours.
The protocol requires that symmetric monitor requests are made to both the local
and remote daemon in order to establish a monitored relationship. This is
convenient for the NFS locking protocol, but probably reduces the usefulness
of the monitoring system for other applications.
The current implementation uses more than 1Kbyte per monitored host in the
status file (and also in VM). This may be inefficient for NFS servers with
large numbers of clients.