1.检查确认要删除的磁盘组是否在用

select * from dba_data_files;
select * from dba_temp_files;
select * from v$logfile;

2.先在各节点上dismount磁盘组

alter diskgroup REDO01 dismount;
alter diskgroup REDO02 dismount;
alter diskgroup REDODG1 dismount;

3.ASM中删除磁盘组

drop diskgroup REDO01 force including contents;
drop diskgroup REDO02 force including contents;
drop diskgroup REDODG1 force including contents;

4.crs删除磁盘组

crsctl stat res -t  ---查看磁盘组
srvctl remove diskgroup -g REDO01 -f
srvctl remove diskgroup -g REDO02 -f
srvctl remove diskgroup -g REDODG1 -f

5.更新crs信息
查看crs依赖的磁盘组：

crsctl status res ora.veraa.db -f
START_DEPENDENCIES=hard(ora.testDG1.dg,ora.testDG2.dg,ora.REDODG1.dg,ora.testDG3.dg,ora.REDO01.dg,ora.REDO02.dg,ora.REDODG01.dg) weak(type:ora.listener.type,global:type:ora.scan_listener.type,uniform:ora.ons,global:ora.gns) pullup(ora.testDG1.dg,ora.testDG2.dg,ora.REDODG1.dg,ora.testDG3.dg,ora.REDO01.dg,ora.REDO02.dg,ora.REDODG01.dg)
START_TIMEOUT=600
STATE_CHANGE_TEMPLATE=
STOP_DEPENDENCIES=hard(intermediate:ora.asm,shutdown:ora.testDG1.dg,shutdown:ora.testDG2.dg,shutdown:ora.REDODG1.dg,shutdown:ora.testDG3.dg,shutdown:ora.REDO01.dg,shutdown:ora.REDO02.dg,shutdown:ora.REDODG01.dg)

修改正确的磁盘组：
srvctl modify database -d veraa -a "testDG1,testDG2,testDG3,REDODG01"