You must install a Management Agent on a host that has a connection to the External Database. Database Management will use the Management Agent for operations such as collecting data and metrics from the External Database.

Note that for single instance databases, a Management Agent 201215.1850 or later is required and for RAC databases, a Management Agent 210403.1349 or later is required. A Management Agent 210403.1349 or later is required for External Databases to use AWR Explorer.

If you encounter issues when installing the Management Agent, see Errors Encountered When Enabling Database Management for External Databases for the likely cause and solution.

SQL> GRANT CREATE PROCEDURE TO dbsnmp;
Grant succeeded.
SQL> GRANT SELECT ANY DICTIONARY, SELECT_CATALOG_ROLE TO dbsnmp;
Grant succeeded.
SQL> GRANT ALTER SYSTEM TO dbsnmp;
Grant succeeded.
SQL> GRANT ADVISOR TO dbsnmp;
Grant succeeded.
SQL> GRANT EXECUTE ON DBMS_WORKLOAD_REPOSITORY TO dbsnmp;
Grant succeeded.
SQL> GRANT CREATE SESSION TO dbsnmp;
Grant succeeded.
SQL> alter user dbsnmp account unlock;
User altered.
SQL> alter user dbsnmp identified by "<password>";
User altered.

Configure Gradual Password Rollover

For Oracle Databases 19c and later, it's recommended that you define a gradual password rollover time, which allows you to connect to the database using both the old and new passwords during the gradual rollover time period. Since both the old and new passwords are valid for some time, downtime is minimized. Using a gradual password rollover, you can avoid any disruptions in the use of Database Management features for your databases.

Note that you can use TCPS protocol to securely create a connection to the Oracle Database and monitor and manage it.