Reconfigure Oracle EM

When you’ve installed Oracle Database 11G as well you can’t change the Windows Host name without reinstalling Oracle Enterprise Manager.

1. Change the %ORACLE_HOME%\network\admin\listener.ora file from an IP number to machine name.
2. Change the %ORACLE_HOME%\network\admin\tnsnames.ora file from an IP number to a machine name.
3. Change the C:\WINDOWS\System32\drivers\etc\hosts file by adding this line beneath the default localhost line
  
127.0.0.1       localhost
192.168.50.1    servername.domain.xyz
Reboot the machine, and then drop the em configuration with the following commands:


C:\admin> set ORACLE_SID=orcl
C:\admin> emca -deconfig dbcontrol db -repos drop

You should then drop the SYSMAN user manually because it doesn’t happen without your assistance (or, it didn’t happen when I did it). If you don’t drop the SYSMAN schema, you’ll raise an error when you try to recreate it:

STARTED EMCA at Aug 23, 2012 1:26:42 AM
EM Configuration Assistant, Version 11.1.0.5.0 Production
Copyright (c) 2003, 2005, Oracle.  All rights reserved.

Enter the following information:
Database SID: orcl
Listener port number: 1521
Password for SYS user:
Password for SYSMAN user:
Password for SYSMAN user:
Do you wish to continue? [yes(Y)/no(N)]: y

Error Like

CONFIG: ORA-20001: SYSMAN already EXISTS..
ORA-06512: at line 17

oracle.sysman.assistants.util.sqlEngine.SQLFatalErrorException: ORA-20001: SYSMAN already EXISTS..
ORA-06512: at line 17

Drop the user and dependent on version a few other objects, like;

DROP USER sysman CASCADE;
DROP PUBLIC SYNONYM setemviewusercontext;
DROP ROLE mgmt_user;
DROP PUBLIC SYNONYM mgmt_target_blackouts;
DROP USER mgmt_view;

You can then create the em environment with the following syntax:

C:\admin> emca -config dbcontrol db -repos create

 Again, you’ll receive the following prompts, enter the Oracle SID and Port number without double quotes but you must enter all passwords with double quotes (at least in Oracle Database 11g):

STARTED EMCA at Aug 23, 2012 1:26:42 AM
EM Configuration Assistant, Version 11.1.0.5.0 Production
Copyright (c) 2003, 2005, Oracle.  All rights reserved.
 
Enter the following information:
DATABASE SID: orcl
Listener port NUMBER: 1521
Password FOR SYS USER:
Password FOR DBSNMP USER:
Password FOR SYSMAN USER:
Password FOR SYSMAN USER: Email address FOR notifications (optional):
Outgoing Mail (SMTP) server FOR notifications (optional):
-----------------------------------------------------------------

You have specified the following settings

DATABASE ORACLE_HOME ................ C:\product\oracle\11.1.0\db_1
 
LOCAL hostname ................ servername
Listener port NUMBER ................ 1521
DATABASE SID ................ orcl
Email address FOR notifications ...............
Outgoing Mail (SMTP) server FOR notifications ...............

Do you wish TO continue? [yes(Y)/no(N)]: y

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How to backup mode enable/disable

ALTER DATABASE BEGIN BACKUP; -- to enter the backup mode.

select file#,status from v$backup;
FILE# STATUS
---------- ------------------
1 ACTIVE
2 ACTIVE
3 ACTIVE
4 ACTIVE

All the data files are in backup mode now


ALTER DATABASE END BACKUP; -- to exit from the backup mode.


select file#,status from v$backup;
FILE# STATUS
---------- ------------------
1 NOT ACTIVE
2 NOT ACTIVE
3 NOT ACTIVE
4 NOT ACTIVE

All the data files are out of backup mode now.

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Receiving Error 'ORA-01041: internal error. hostdef extension doesn't exist.' on re-establishing a connection to Oracle.

You can receive the error message 'Error ORA-01041: internal error. hostdef extension doesn't exist' when attempting to re-establish a connection to Oracle with ERwin. This can happen for example when repeating the Complete Compare process.

Solution:
Locate the 'sqlnet.ora' file and set:

SQLNET.AUTHENTICATION_SERVICES = (NONE)  

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