1Z0-053 争议题目解析541
考试科目：1Z0-053
题库版本：V13.02
题库中原题为：
541.If you use ALTER DISKGROUP ... ADD DISK and specify a wildcard for the discovery string, what
happens to disks that are already a part of the same or another disk group?
A. The command fails unless you specify the FORCE option.
B. The command fails unless you specify the REUSE option.
C. The command must be reissued with a more specific discovery string.
D. The other disks, already part of the disk group, are ignored.
Answer: D
争议点：
网上有人说应该选择A。
比如：
LuiseDalian的解析：http://blog.itpub.net/17013648/viewspace-1314073/
Riveore的解析：http://blog.csdn.net/rlhua/article/details/15020267
我个人实验感觉应该C选项更合适。
实验环境：11.2.0.4 ASM
当前没有11.2.0.1的环境，不确定是否小版本差异是否会影响到实验结果。
SQL> --查询磁盘组及其相关联的底层设备
SQL> set linesize 140
SQL> col path for a66
SQL> select group_number, disk_number, mount_status, name, path
2 from v$asm_disk
3 order by group_number, disk_number;
GROUP_NUMBER DISK_NUMBER MOUNT_S NAME PATH
------------ ----------- ------- ------------------------------ ------------------------------------------------------------------
0 2 CLOSED /dev/mapper/ora_vg-lv_asm5
0 3 CLOSED /dev/mapper/ora_vg-lv_asm3
0 4 CLOSED /dev/mapper/ora_vg-lv_asm6
0 5 CLOSED /dev/mapper/ora_vg-lv_asm4
1 0 CACHED D1A /dev/mapper/ora_vg-lv_asm1
1 1 CACHED D1B /dev/mapper/ora_vg-lv_asm2
6 rows selected.
SQL> desc v$asm_diskgroup;
Name Null? Type
----------------------------------------------------------------------------- -------- ----------------------------------------------------
GROUP_NUMBER NUMBER
NAME VARCHAR2(30)
SECTOR_SIZE NUMBER
BLOCK_SIZE NUMBER
ALLOCATION_UNIT_SIZE NUMBER
STATE VARCHAR2(11)
TYPE VARCHAR2(6)
TOTAL_MB NUMBER
FREE_MB NUMBER
HOT_USED_MB NUMBER
COLD_USED_MB NUMBER
REQUIRED_MIRROR_FREE_MB NUMBER
USABLE_FILE_MB NUMBER
OFFLINE_DISKS NUMBER
COMPATIBILITY VARCHAR2(60)
DATABASE_COMPATIBILITY VARCHAR2(60)
VOTING_FILES VARCHAR2(1)
SQL> select name from v$asm_diskgroup;
NAME
------------------------------
DATA1
--1.直接添加失败，并没有忽略已经在磁盘组中的磁盘
SQL> ALTER DISKGROUP DATA1 ADD DISK '/dev/mapper/ora_vg-lv_asm*';
ALTER DISKGROUP DATA1 ADD DISK '/dev/mapper/ora_vg-lv_asm*'
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15029: disk '/dev/mapper/ora_vg-lv_asm1' is already mounted by this instance
--2.加入FORCE也不行
SQL> ALTER DISKGROUP DATA1 ADD DISK '/dev/mapper/ora_vg-lv_asm*' FORCE;
ALTER DISKGROUP DATA1 ADD DISK '/dev/mapper/ora_vg-lv_asm*' FORCE
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15029: disk '/dev/mapper/ora_vg-lv_asm1' is already mounted by this instance
--3.指定具体盘符可以
SQL> ALTER DISKGROUP DATA1 ADD DISK '/dev/mapper/ora_vg-lv_asm3';
Diskgroup altered.
SQL> select group_number, disk_number, mount_status, name, path
2 from v$asm_disk
3 order by group_number, disk_number;
GROUP_NUMBER DISK_NUMBER MOUNT_S NAME PATH
------------ ----------- ------- ------------------------------ ------------------------------------------------------------------
0 2 CLOSED /dev/mapper/ora_vg-lv_asm5
0 4 CLOSED /dev/mapper/ora_vg-lv_asm6
0 5 CLOSED /dev/mapper/ora_vg-lv_asm4
1 0 CACHED D1A /dev/mapper/ora_vg-lv_asm1
1 1 CACHED D1B /dev/mapper/ora_vg-lv_asm2
1 2 CACHED DATA1_0002 /dev/mapper/ora_vg-lv_asm3
6 rows selected.
初步结论：
保留争议，选择C。