how to replace disks in external diskgroug redundency

Hi Folks,

we are running oracle RAC 11.2.0.4.0 on 2 node at IBM 7.1. our requirement is to add new disks to  external diskgroups &  drop the the current disks from external diskgroups, please  validate the below steps & correct me if you find something wrong or assist me the steps.

currently we have  like below

sqlplus / as sysasm

SELECT SUBSTR(d.name,1,16) AS asmdisk,d.TOTAL_MB, d.FREE_MB,

     dg.name AS diskgroup FROM V$ASM_DISKGROUP dg, V$ASM_DISK d

     WHERE dg.group_number = d.group_number;SQL>   2    3

ASMDISK            TOTAL_MB    FREE_MB DISKGROUP

---------------- ---------- ---------- ------------------------------

DATA_0002            102400      24028 DATA

DATA_0004            102400      24030 DATA