Managing Database Resources - OCP: Oracle Database 12c Administrator Certified Professional - page 482

Step 3: Start the Source Database in Read-Only Mode
When you're ready to start the migration, you'll need to shut down the source database and
open it in read-only mode.
SQL> shutdown immediate;
SQL> startup mount;
SQL> alter database open read only;
At this point, you have not started the migration to the destination system, and you
haven't made any changes to the source system. If you run into problems and need to return
to normal operations in the source system, this would be your “rollback” point.
Step 4: Verify That the Database Is Ready for Migration
Now you need to verify that the source database is in fact ready for migration to the destina-
tion. Execute the DBMS_TDB.CHECK_DB function, providing the destination system PLATFORM_
NAME exactly as shown in the V$DB_TRANSPORTABLE_PLATFORM view. If the CHECK_DB function
returns an error condition, you must fix it before you can continue the migration.
SQL> set serveroutput on
SQL> declare
tdb_check boolean;
begin
tdb_check := dbms_tdb.check_db
('Linux IA (64-bit)',dbms_tdb.skip_none);
end;
/
Database is not open in READ-ONLY mode. Open the database
in READ-ONLY mode and retry.
PL/SQL procedure successfully completed.
The results show that you didn't start the database in read-only mode, so you must fix
that and rerun the PL/SQL block before moving to the next step.
If you're using a physical standby database for the migration source, run the
DBMS_TDB.CHECK_DB function on the standby, not the primary. Follow this
general rule for the remainder of this section unless otherwise indicated.
If you're migrating from a physical standby database, use the physical
standby, not the primary database, wherever we refer to the source.
Step 5: Run RMAN CONVERT DATABASE
With the RMAN conversion, you'll run either a source-system or destination-system
conversion. We'll describe the process for both, starting with the source-system and then
the destination-system approach.