ASM接触了很长时间，从磁盘组中删除磁盘的操作还是第一次。
没想到这么简单的操作，由于不熟悉还碰到了两个小问题。
[oracle@dbserver1 ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Tue Aug 9 10:08:06 2011
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP, Data Mining
and Real Application Testing options
SQL> set pages 100 lines 120
SQL> select group_number, name, state, type, total_mb, free_mb
2 from v$asm_diskgroup;
GROUP_NUMBER NAME STATE TYPE TOTAL_MB FREE_MB
------------ ------------------------------ ----------- ------ ---------- ----------
1 DATA_AU1M CONNECTED EXTERN 1953124 7430
2 DATA_AU2M CONNECTED EXTERN 1953124 7384
3 DATA_AU4M CONNECTED EXTERN 1953124 7304
4 DATA CONNECTED EXTERN 3906248 3898966
SQL> col path format a30
SQL> col name format a30
SQL> select disk_number, path, name, total_mb, free_mb
2 from v$asm_disk
3 where group_number = 4;
DISK_NUMBER PATH NAME TOTAL_MB FREE_MB
----------- ------------------------- ------------------------- ---------- ----------
1 /dev/asm-disk5 DATA_0001 1953124 1949486
0 /dev/asm-disk4 DATA_0000 1953124 1949480
SQL> alter diskgroup data drop disk '/dev/asm-disk5';
alter diskgroup data drop disk '/dev/asm-disk5'
*
ERROR at line 1:
ORA-15000: command disallowed by current instance type
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP, Data Mining
and Real Application Testing options
由于当前连接的是数据库，显然不能对ASM实例中的磁盘组进行操作，下面连接ASM实例：
[oracle@dbserver1 ~]$ su - grid
Password:
[grid@dbserver1 ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.2.0 Production on Tue Aug 9 10:12:39 2011
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Automatic Storage Management option
SQL> set pages 100 lines 120
SQL> select instance_number, instance_name from v$instance;
INSTANCE_NUMBER INSTANCE_NAME
--------------- ----------------
1 +ASM
SQL> alter diskgroup data drop disk '/dev/asm-disk5';
alter diskgroup data drop disk '/dev/asm-disk5'
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15260: permission denied on ASM disk group
SQL> alter diskgroup data drop disk data_0001;
alter diskgroup data drop disk data_0001
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15260: permission denied on ASM disk group
开始看到这个错误还确实疑惑了一下，怎么可能没有权限。有在操作系统上检查了磁盘的权限，也没有任何问题。
检查Oracle文档的错误信息后发现，由于习惯了适用sysdba来处理，忽略了当前是11g的ASM，应该用sysasm来登录：
SQL> conn / as sysasm
Connected.
SQL> alter diskgroup data drop disk data_0001;
Diskgroup altered.
SQL> select disk_number, state, name, total_mb, free_mb from v$asm_disk where group_number = 4;
DISK_NUMBER STATE NAME TOTAL_MB FREE_MB
----------- -------- ------------------------------ ---------- ----------
1 DROPPING DATA_0001 1953124 1950842
0 NORMAL DATA_0000 1953124 1948124
SQL> select disk_number, state, name, total_mb, free_mb from v$asm_disk where group_number = 4;
DISK_NUMBER STATE NAME TOTAL_MB FREE_MB
----------- -------- ------------------------------ ---------- ----------
1 DROPPING DATA_0001 1953124 1951434
0 NORMAL DATA_0000 1953124 1947532
SQL> select disk_number, state, name, total_mb, free_mb from v$asm_disk where group_number = 4;
DISK_NUMBER STATE NAME TOTAL_MB FREE_MB
----------- -------- ------------------------------ ---------- ----------
1 DROPPING DATA_0001 1953124 1952556
0 NORMAL DATA_0000 1953124 1946410
SQL> select disk_number, state, name, total_mb, free_mb from v$asm_disk where group_number = 4;
DISK_NUMBER STATE NAME TOTAL_MB FREE_MB
----------- -------- ------------------------------ ---------- ----------
1 DROPPING DATA_0001 1953124 1953096
0 NORMAL DATA_0000 1953124 1945870
SQL> select disk_number, state, name, total_mb, free_mb from v$asm_disk where group_number = 4;
DISK_NUMBER STATE NAME TOTAL_MB FREE_MB
----------- -------- ------------------------------ ---------- ----------
0 NORMAL DATA_0000 1953124 1945854
SQL> select group_number, disk_number, path, name, state, total_mb, free_mb
2 from v$asm_disk
3 where path = '/dev/asm-disk5';
GROUP_NUMBER DISK_NUMBER PATH NAME STATE TOTAL_MB FREE_MB
------------ ----------- --------------- ---------- -------- ---------- ----------
0 1 /dev/asm-disk5 NORMAL 0 0
可以看到，虽然删除操作执行完成，但是磁盘并没有真正被删掉，ASM在后台尝试将磁盘上的数据挪到其他可用磁盘中，这时磁盘的状态为DROPPING。
当后台数据同步的操作完成，磁盘的组信息被清除，磁盘恢复STATE状态。这时这个磁盘就从ASM中被彻底删除。
