How to Add/Drop/Resize Redo Log with Physical Standby in place. [ID 473442.1]

	Modified 12-AUG-2009     Type HOWTO     Status REVIEWED

In this Document
  
  

Oracle Server - Enterprise Edition - Version: 10.2.0.1 to 10.2.0.5
Information in this document applies to any platform.

To Add/Drop/Resize online redo logs in the primary site with physical standby database in place. What are the steps to be done on standby if any?

Changing the size of redo involves adding the new sized log and dropping the unwanted old log. There is no resize command as such. You can add or drop online redo log file groups or members to the primary database without affecting the standby database. Similarly, you can drop log file groups or members from the primary database without affecting your standby database. However, these changes do affect the performance of the standby database after a role transition. So it is best advised whenever you add an online redo log file to the primary database, you should add corresponding online and standby redo 
log files to the standby database.

To resize redo logs the steps are as follows:

At the primary site

=============

1. Set STANDBY_FILE_MANAGEMENT to MANUAL. 
SQL> ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='MANUAL'; 


2. Add the new redo logfile groups of the required sizes.
SQL> ALTER DATABASE ADD LOGFILE GROUP 4 ('/U01/oracle/modg1/redo04.log') SIZE 50M;

3. Drop the old groups, this may involve performing log switches to ensure the old logs have been archived correctly or could be performed later once oracle has finished with the logs.
SQL>ALTER DATABASE DROP LOGFILE GROUP 2;

4. Set STANDBY_FILE_MANAGEMENT to AUTO. 
SQL> ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='AUTO';

At the standby site

=============
1. Stop Redo apply: 

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL; 

2. Set STANDBY_FILE_MANAGEMENT to MANUAL. 
SQL> ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='MANUAL'; 

3. Add Redolog File Group: 
SQL> ALTER DATABASE ADD LOGFILE GROUP 4 ('/U01/oracle/modg1/redo04.log') SIZE 50M; 

Add as many Redo Logfile Groups (or Members) you want to add. 

4. Set STANDBY_FILE_MANAGEMENT to AUTO. 
SQL> ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='AUTO'; 

5. Check the Status of the Online Redolog Group. 
SQL> SELECT GROUP#, STATUS FROM V$LOG; 

GROUP# STATUS 
---------- ---------------- 
1 CLEARING_CURRENT 
3 CLEARING 
2 CLEARING 

If Status is CLEARING_CURRENT then you cannot drop Online Redolog Group. You will get ORA-01623 if you try to drop a Redolog Group with Status CLEARING_CURRENT.

For Status CLEARING, UNUSED, INACTIVE please follow below steps. 

6. Clear the Online Redo Logfile Group: 
SQL> ALTER DATABASE CLEAR LOGFILE GROUP 2; 

7. Drop the Online Redo Logfile Group: 
SQL>ALTER DATABASE DROP LOGFILE GROUP 2; 

If you have skipped Step 4 then you will get ORA-01624 while droping the Online Redolog Group with Status CLEARING. 

8. Set STANDBY_FILE_MANAGEMENT to AUTO. 
SQL> ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='AUTO'; 

9. Start Redo Apply: 
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;