Synchronizing redo changes from the primary database to the standby database

Changing the size and number of the online redo log files is sometimes done to tune the database. 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 the standby database. However, these changes can affect the performance of the standby database after switchover.

For example, the primary database has 10 redo log files and the standby database has two online redo log files. When you switch over to the standby database so that it functions as the new primary database, the new primary database is forced to archive more frequently than the original primary database.

We strongly recommend that if you add or drop online redo log files from the primary database, you synchronize the changes on the standby database.

To synchronize redo changes from the primary database to the standby database

If Redo Apply is running, you must cancel it before you can change the log files. In sqlplus on the standby server, execute the command:
alter database recover managed standby database cancel;
If the STANDBY_FILE_MANAGEMENT initialization parameter is set to AUTO, to change the value to MANUAL, execute the command:
alter system set standby_file_management = manual;
To add or drop an online redo log file, execute the commands:
connect internal
To check the existing redo log groups, execute the command
select * from v$log;
To determine the location and the file names of the current redo log files, execute the command
select * from v$logfile;
To add a new online redo log file, execute the command
alter database add logfile 'usr/mvf/data/dbase/redo/redo#.log' size 25000K; (Solaris) or alter database add logfile 'd:\data\dbase\redo\redo#.log' size 25000K; (Windows)

Where # is the number of the next redo log group. For example, if the select * from v$logfile; command returns redo03, you would create redo04.
To add more redo log files, repeat steps 5 and 6.
To switch to the current log file, execute the command:
alter system switch logfile;
If the redo log needs to be dropped, execute the commands:
alter database drop logfile group #;
select * from v$log;

Where # specifies the log group to drop, for example, alter database drop logfile group 1; drops the redo01.log file
To restore the STANDBY_FILE_MANAGEMENT initialization parameter and the Redo Apply options to their original states, execute the commands:
alter database recover managed standby database using current logfile disconnect from session;
alter system set standby_file_management = auto;