Hello friends, this week we are going to add a Redo log group, also steps to drop redo log groups. In RAC, each instance has a redo thread; when you start the instance, it mounts one and only one thread. Therefore, if you want to add logs or increase the size, you must do it for each thread. The goal is normally to have the same number and size of logs for each thread.
First, determine what log members each thread has. Here is a sample of a script to show what log members you currently have and their sizes:
Sample output:
Steps to add redo log groups to Oracle RAC setup
Check existing redo log groups & redo log file size.
- As we checked redo log file location & size, we will proceed for redo log group addtions, we will add group 5 and 6 & thread 1 and 2 for this example.
We can use below commands also:
ALTER DATABASE ADD LOGFILE THREAD 1 GROUP 5 ‘+REDO’ SIZE 100m;
ALTER DATABASE ADD LOGFILE THREAD 1 GROUP 6 ‘+REDO’ SIZE 100m;
ALTER DATABASE ADD LOGFILE THREAD 2 GROUP 7 ‘+REDO’ SIZE 100m;
ALTER DATABASE ADD LOGFILE THREAD 2 GROUP 8 ‘+REDO’ SIZE 100m;
- Check for newly added redo log groups:
Steps to drop redo log groups
- While dropping redo log group & we need to check the status of redo log groups. redo log group status should be INACTIVE or UNUSED.
select group#,thred#,members,status from v$log;
- To drop inactive/unused redo log group:
Alter database drop logfile group 1;
- Check again to verify the redo log groups:
select group#,thred#,members,status from v$log;
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Source: https://docs.oracle.com/cd/E18283_01/server.112/e17120/onlineredo003.htm