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July - September, 2008 Status Reports
11-11-2008
About Ganglia Monitor Daemon|
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esmd(1M) esmd(1M) NAME
esmd - Essential Services Monitor (ESM) Daemon SYNOPSIS
retry_seconds] DESCRIPTION
The Essential Services Monitor (ESM) daemon, maintains the availability of essential system daemons by automatically restarting them if they terminate. The ESM daemon monitors the Event Manager daemon, The ESM daemon is started by the init process when the system is ini- tialized to run level 2 and continues to run until the system is shut down or returned to single user mode. Only one instance of can run at a time. Configuration information is sent to the ESM daemon by a control program, which is run at key points in the startup and shutdown proce- dures. As startup or shutdown progresses, the control program updates the ESM state file, The control program then signals the daemon to reconfigure itself. On startup, state transitions occur after has started. On shutdown, transitions occur after each of these monitored daemons has termi- nated. After each transition, the ESM daemon determines which of the monitored daemons should be running and adjusts its monitoring activ- ities 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(1M) 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. The ESM daemon peri- odically 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, the ESM daemon again attempts to restart it. The ESM daemon can be forced to restart a failed daemon by sending a SIGHUP signal to the process. If there is a need to temporarily disable the ESM daemon for test purposes, in order to prevent the monitored daemons from being restarted automatically, send a SIGSTOP signal to the process. To reactivate the ESM daemon, send a SIGCONT signal to the process. The ESM daemon should never be disabled on a production system. If the ESM daemon is terminated unexpectedly, it is restarted automatically by init. Options The command recognizes the following options: Limit the priority of any syslog messages posted by the ESM daemon to "alert." If this option is not specified, posts an "emergency" message if it cannot restart a failed daemon. A message may be sent to all users currently logged in to the system. The option should only be used if the system administrator is actively monitoring syslogd messages. Specify the interval between attempts to begin monitoring a daemon that has failed, and which has been unable to restart automatically. The default period is 30 seconds. Specifying a period of zero disables retrying. Notes To use the start options, you must add them to the startup command in the file. The daemon reports any invalid start options with a single generic message through syslogd. Restrictions 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. Only one instance of can run at a time. RETURN VALUE
The following exit values are returned: 0 (Zero) Successful completion. not 0 An error occurred. FILES
Executable file Configuration control script Initialization process control file dispatched by boot init Monitoring state file Receives esmd status messages AUTHOR
was developed by Hewlett Packard Company. SEE ALSO
Commands kill(1), evmd(1M), init(1M), syslogd(1M). Files inittab(4). esmd(1M)