SQL> drop diskgroup sysdata;
drop diskgroup sysdata
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15001: diskgroup "SYSDATA" does not exist or is not mounted

SQL> drop diskgroup flaskback;
drop diskgroup flaskback
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15001: diskgroup "FLASKBACK" does not exist or is not mounted
--查看状态显示为DISMOUNTED
SQL> select name,state from v$asm_diskgroup;

NAME                           STATE
------------------------------ -----------
SYSDATA                        DISMOUNTED
FLASKBACK                   DISMOUNTED
---mount磁盘组的状态
SQL> alter diskgroup flaskback mount;
Diskgroup altered.
---再次删除依然提示错误 含有文件。
SQL> drop diskgroup flaskback;
drop diskgroup flaskback
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15053: diskgroup "FLASKBACK" contains existing files
---只要使用含有including contents子句删除就可以了
SQL> drop diskgroup flaskback including contents;
Diskgroup dropped.
---system 磁盘组也一样。。
SQL> drop diskgroup sysdata including contents;
drop diskgroup sysdata including contents
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15001: diskgroup "SYSDATA" does not exist or is not mounted
SQL> alter diskgroup sysdata mount;
Diskgroup altered.
SQL> drop diskgroup sysdata including contents;
Diskgroup dropped.