Grid Control

Definitions

OMS - Management Service - This is responsible for communicating with the user via a GUI and communicating with the OMR
OMR - Management Repository - This is a collection of tables owned by the sysman schema that stores all the data collected by the OMA
OMA - Management Agent - This is a perl program that runs on the database host (one for all databases on the host) and uploads data to the OMS

From SQL*Plus:
select username,program from v$session where LOWER (program) like 'emagent%';

If no rows selected, the agent is not running. or

From Unix:
. oraenv
agent11g (how to find what SIDs are available on your machine)
emctl status agent

ps -ef|grep [a]gent

There should be a handful. If only a few, kill them and restart the agent.

emctl start agent

Check the agent log in $ORACLE_HOME/sysman/log

emctl config agent listtargets

It looks at the file $AGENT_HOME/sysman/emd/targets.xml

Manually add targets by editing the file $AGENT_HOME/sysman/emd/targets.xml and running:

emctl config agent addtargets $AGENT_HOME/sysman/emd/targets.xml

Check state and upload directories under $AGENT_HOME/sysman/emd for .err files

Master Index for Managing Oracle Database and Listener with Grid Control [ID 1304021.1]
Master Note for 10g Grid Control Agent Process Control (Start, Stop & Status) & Configuration [ID 1082009.1]
How to Run the RDA against a Grid Control Installation [ID 1057051.1]
How to Run the RDA against a Grid Control Installation Release 11g [ID 1190193.1]
Grid Control Target Maintenance: Steps to Diagnose Issues Related to "Agent Unreachable" Status [ID 271126.1]
Master Note for 10g Grid Control Enterprise Manager Communication and Upload issues [ID 1086343.1]
Master Note for Target Maintenance Through 10g Enterprise Manager Grid Control [ID 1202453.1]
Receiving agent unreachable notification emails very often after 10.2.0.4 agent upgrade [ID 752296.1]
Healthcheck Metric failing for a 10.2.0.4 Target Database with 10.2.0.4 Agent [ID 602633.1]