To add a new member to each group use OEM console
1. Navigate to Storage
2. Click the Redo Log Groups folder.
3. Select Create from the right-mouse menu.
4. Select the General tabbed page.
5. Complete the information to create the online redo log file group
and/or members.
6. Click Create.



To change the size of the redo log members your will have to create new
groups with the new size, and drop the old ones.

Before dropping the redo log group, make sure that the group in not
active or current.

Select * from v$log;
If not inactive log file groups, use this command
ALTER SYSTEM SWITCH LOGFILE;
Confirm: Select * from v$log;
then
ALTER DATABASE DROP LOGFILE GROUP x;

Creating new Groups

ALTER DATABASE ADD LOGFILE
GROUP 1 ('/redologs/redo0101.log',
'/epic/clarity/redologs/redo0102.log') SIZE 150M;
GROUP 2 ('/redologs/redo0201.log',
'/epic/clarity/redologs/redo0202.log') SIZE 150M;
GROUP 3 ('/redologs/redo0301.log',
'/epic/clarity/redologs/redo0302.log') SIZE 50M;
GROUP 4 ('/redologs/redo0401.log',
'/epic/clarity/redologs/redo0402.log') SIZE 150M;

Since an instance requires at least two groups of online redo log
files, you will be better off creating the new groups with a slightly
different name and then dropping the old groups.




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