redo log groups

Hi All,

Thanks for helping.

Actually i have doubt. Please find my enivronment.

SQL> select name,open_mode from v$database;

NAME OPEN_MODE
--------- ----------
PRLT0 READ WRITE

SQL> select MEMBER from v$logfile;

MEMBER
--------------------------------------------------------------------------------
+DG_01/PRLT0/onlinelog/redo02.log
+DG_01/PRLT0/onlinelog/redo01.log
+DG_01/PRLT0/onlinelog/redo03.log
+DG_01/PRLT0/onlinelog/redo04.log

SQL> select instance_number, instance_name, thread# from gv$instance;

INSTANCE_NUMBER INSTANCE_NAME THREAD#
--------------- ---------------- ----------
2 PRLT02 2
1 PRLT01 1

SQL> select group#, thread#, members ,status from v$log;

GROUP# THREAD# MEMBERS STATUS
---------- ---------- ---------- ----------------
1 1 1 INACTIVE
2 1 1 CURRENT
3 2 1 INACTIVE
4 2 1 CURRENT

I want to add four redo log groups per instance.
Totally have to add 8 redo log groups for two node cluster.

Please command to add the redo log groups:-
=========================================
ALTER DATABASE ADD LOGFILE THREAD 1 GROUP 5 ('+DG_01') SIZE 256M;

My question when have to add this one?
whether i have change anything before adding?

Thanks & Regards,
Indira Shyamsundar