Multiplex online Redo Logfile

It is important to have multiple (at list two) copy of each online redo logfile. To avoid the disaster of disk failure, it is recommended to place each member of a specific online redo logfile group in different disk.

To view to current online redo logfile group members

SELECT GROUP#,STATUS,MEMBER FROM V$LOGFILES;

Suppose we have disk01 (mount point /u01 ) that contains current online redolog files .To add member in redo logfile group 1,2 and 3 in disk02 ( mount point /u02 )

ALTER DATABASE ADD LOGFILE MEMBER '/u02/redo01.log' TO GROUP 1;
ALTER DATABASE ADD LOGFILE MEMBER '/u02/redo02.log' TO GROUP 2;
ALTER DATABASE ADD LOGFILE MEMBER '/u02/redo03.log' TO GROUP 3;