HP-UX Event ManagerAdministrator's Guide

Introduction
Overview
Chapter 1 19
Passive event channels do not post events and must be polled for
information. These channels are depicted by the log files handled by the
monitor scripts.
The primary component of the Event Manager is the evmd daemon,
which is initialized when the system is booted to run level 2. For event
management to function during system startup, the initialization of the
daemon and its child processes is synchronized as follows:
• When you boot the system, some kernel components post events as
part of their initialization sequences. These events are queued in the
kernel memory until the daemon is ready to accept them, because
the daemon is not yet running.
• The daemon starts early in the run level 2 initialization sequence of
system startup. When the daemon starts, it performs the following
actions:
— Starts the logger
— Starts the channel manager
— Listens for connection requests from clients
• After the logger establishes its listening connection and is ready to
log events, the daemon begins accepting posted events from the
kernel and user-level posters.
The Event Manager logger, evmlogger, is an essential system component
and must never be deconfigured, because some system components rely
on its operation.
The logger program, evmlogger, runs as a resident process. It is
configured to subscribe to a selected set of events, and to store them in
managed log files for later retrieval. By default, the logger is configured
to do the following:
• Write high-priority events to the system console
• Send mail to the system administrator when high-priority events
occur
The resident channel manager process, evmchmgr, is configured to run
periodic channel-monitoring scripts, which post events when they detect
noteworthy activity in the channel. The channel manager also runs the
daily log cleanup functions.