Here are my notes related to the OEM.
From Oracle 10g, Oracle introduce the web base management tool to replace the java base client. The application is called “Oracle Enterprise Manager”.
There are two version of OEM.
- Oracle Enterprise Manager Database Control ( OEM Database Control )
- Oracle Enterprise Manager Grid Control ( OEM Grid Control )
OEM Database control is the single host Database management console. We can configure during the dbca or through the emca.
OEM Grid Control is advance version of OEM. It can manage multiple host database and other Oracle application such as E-Business Suit.
How to find the current OEM port number
This file is updated by emca in the creation process or through emca –configure ports
OEM Database Control Directory structure
- $ORACLE_HOME\sysman\admin -> OEM Share management files
- $ORACLE_HOME\hostname_sid\sysman –> OEM management files for $ORACLE_SID
- $ORACLE_HOME\oc4j\j2ee\oc4j_DBConsole –> DBConsole template
- $ORACLE_HOME\oc4j\j2ee\oc4j_DBConsole_hostname_sid -> DBConsole $ORACLE_SID files
emctl status dbconsole
emctl start dbconsole
emctl stop dbconsole
Enterprise Manager has dependence on the listener. If listener is not running, we can not login to the Enterprise manager as EM require connects to database to verify the password. If the listener is started after the EM started, we can login to the EM but the agent would fail connect to TNS. In this case, we need to bounce the EM.
If listener is not in the default port ( 1521), you can see the error message in the emagent.trc .
dbversion is 11dbversion is not 9em_error=Could not connect to dbsnmp/(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=panda1.localdomain)(Port=1521))(CONNECT_DATA=(SID=oracledb1)))
: ORA-12541: TNS:no listener (DBD ERROR: OCIServerAttach)