esmd - Essential Services Monitor daemon
/usr/sbin/esmd [-a] [-r retry_seconds]
Limits the priority of any syslog messages posted by the
ESM daemon to "alert." If this option is not specified,
esmd will post an "emergency" message if it cannot restart
a failed daemon, which may result in a message being sent
to all users currently logged in to the system. The -a
option should only be used if the system administrator is
actively monitoring syslogd messages. Specifies the
interval between attempts to begin monitoring a daemon
that has failed, and which esmd has been unable to restart
automatically. The default period is 30 seconds. Specifying
a period of zero disables retrying.
None.
The Essential Services Monitor (ESM) daemon, esmd, maintains
the availability of essential system daemons by
automatically restarting them if they terminate. The ESM
daemon monitors the Event Manager daemon, evmd, and, in a
cluster environment, the Cluster Application Availability
(CAA) daemon, caad.
The ESM daemon is started by the init process when the
system is initialized to run level 2 and continues to run
until the system is shut down or returned to single user
mode. If the daemon terminates, it is restarted automatically
by init.
Configuration information is sent to the ESM daemon by a
control program, /sbin/init.d/esm, which is run at key
points in the startup and shutdown procedures. As startup
or shutdown progresses, the control program updates the
ESM state file, /var/run/esm.state and signals the daemon
to reconfigure itself.
On startup, state transitions occur after evmd has started
and, in a cluster environment, after caad has started. On
shutdown, transitions occur after each of these monitored
daemons has terminated. After each transition, the ESM
daemon determines which of the monitored daemons should be
running and adjusts its monitoring activities accordingly.
The ESM daemon reports all state change information,
including notice of failures and restarts, through the
system logging daemon, syslogd. Messages are displayed on
the system console during periods when syslogd is not running.
See syslogd(8) for more information.
If the ESM daemon fails to restart a monitored daemon, it
reports the error by posting a high priority message
through syslogd, and makes no further restart attempts.
The system administrator should investigate the problem
and restart the failed daemon. ESM periodically attempts
to resume monitoring of the daemon, and posts an informational
message when it succeeds. If the monitored daemon
fails again once monitoring has resumed, ESM will again
make one attempt to restart it.
ESM can be forced to restart a failed daemon by sending a
SIGHUP signal to the esmd process.
If there is a need to temporarily disable the ESM daemon
for test purposes, to prevent the monitored daemons from
being restarted automatically, send a SIGSTOP signal to
esmd. To reactivate it, send a SIGCONT signal. The daemon
should never be disabled on a production system.
If you want to use start options, you must add them to the
esmd startup command in the /etc/inittab file. The daemon
reports any invalid start options with a single generic
message through syslogd.
The daemon terminates with an error message if it is
started by any process other than init.
The /sbin/init.d/esm program is intended to be run by the
system startup and shutdown process and should not be run
from the command line.
Success. An error occurred.
Executable file Configuration control script Initialization
process control file Monitoring state file Receives
esmd status messages
Commands: kill(1), caad(8), evmd(8), init(8), syslogd(8)
Files: inittab(4)
esmd(8)
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