环境：3台虚拟机 RHEL 7.3 + Oracle RAC 11.2.0.4
问题现象：RAC运行正常，ASM磁盘组Normal冗余，有failgroup整体故障，有failgroup配置错误。
温馨提示：本文并不是市场上任何一款商业的一体机产品，只是我为了学习这类分布式存储架构自己模拟的实验环境，为了区分我暂时称之为xData吧_。
1.问题现象确认
SQL> select group_number, name, total_mb, free_mb, USABLE_FILE_MB, offline_disks, state, type from v$asm_diskgroup;
GROUP_NUMBER NAME TOTAL_MB FREE_MB USABLE_FILE_MB OFFLINE_DISKS STATE TYPE
------------ ------------------------------ ---------- ---------- -------------- ------------- ---------------------- ----------
1 CRS 2000 1170 585 0 MOUNTED NORMAL
2 DATA 40960 35652 7586 0 MOUNTED NORMAL
SQL> select group_number, disk_number, name, path, failgroup, mode_status, voting_file from v$asm_disk order by 1, 2;
GROUP_NUMBER DISK_NUMBER NAME PATH FAILGROUP MODE_STATUS VO
------------ ----------- ------------------------------ ----------------------- -------------------- -------------- --
0 0 /dev/CELL01-data2 ONLINE N
0 1 /dev/CELL01-data1 ONLINE N
0 2 /dev/CELL01-crs1 ONLINE Y
1 1 CRS_0001 /dev/CELL02-crs2 CRS_0001 ONLINE Y
1 2 CRS_0002 /dev/CELL03-crs3 CRS_0002 ONLINE Y
2 0 DATA_0000 /dev/CELL03-data1 DATA_0000 ONLINE N
2 1 DATA_0001 /dev/CELL03-data2 DATA_0001 ONLINE N
2 2 DATA_0002 /dev/CELL02-data1 CELL02 ONLINE N
2 3 DATA_0003 /dev/CELL02-data2 CELL02 ONLINE N
9 rows selected.
可以看到不但CELL01节点的所有盘被删除，而且CELL03节点的数据盘，failgroup目前也配置不正确！
2.重新加入CELL01的盘
由于时间超过默认的3.6h，offline的盘已经被删除，只有重新加入CELL01的盘才可以。
alter diskgroup CRS add disk '/dev/CELL01-crs1';
alter diskgroup DATA ADD FAILGROUP CELL01 disk '/dev/CELL01-data1', '/dev/CELL01-data2' rebalance power 5;
直接这样加盘很可能会遇到下面这类错误，因为这些盘之前是被使用过的：
SQL> alter diskgroup CRS add disk '/dev/CELL01-crs1';
alter diskgroup CRS add disk '/dev/CELL01-crs1'
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15033: disk '/dev/CELL01-crs1' belongs to diskgroup "CRS"
这个问题可以通过dd盘头，也可以加盘尝试加force参数来解决，我这里选择dd盘头的方式：
[root@db01 ~]# dd if=/dev/zero of=/dev/CELL01-crs1 bs=8k count=1000
1000+0 records in
1000+0 records out
8192000 bytes (8.2 MB) copied, 0.0691801 s, 118 MB/s
dd盘头之后再次尝试添加就可以顺利完成：
SQL> alter diskgroup CRS add disk '/dev/CELL01-crs1';
Diskgroup altered.
同样的，将CELL01的数据盘也重新加入到DATA磁盘组中，failgroup名称为CELL01:
SQL> alter diskgroup DATA ADD FAILGROUP CELL01 disk '/dev/CELL01-data1', '/dev/CELL01-data2' rebalance power 5;
Diskgroup altered.
通过v$asm_operation视图可以查看磁盘重新平衡的进度，直到下面的查询不再返回结果说明重平衡完成：
SQL> select * from v$asm_operation;
GROUP_NUMBER OPERATION STATE POWER ACTUAL SOFAR EST_WORK EST_RATE EST_MINUTES ERROR_CODE
------------ ---------- -------- ---------- ---------- ---------- ---------- ---------- ----------- --------------------
2 REBAL RUN 5 5 366 529 348 0
SQL> select * from v$asm_operation;
no rows selected
3.修改failgroup的配置
CELL03的数据盘，failgroup目前配置还不正确。
SQL> alter diskgroup DATA drop disk DATA_0000, DATA_0001;
Diskgroup altered.
查询v$asm_operation视图可以查看磁盘重新平衡的进度，完成后再重新加回磁盘组，指定确切的failgroup(CELL03)：
SQL> alter diskgroup DATA ADD FAILGROUP CELL03 disk '/dev/CELL03-data1', '/dev/CELL03-data2' rebalance power 5;
Diskgroup altered.
再次关注重平衡进度，最后查询一切正常，结果如下：
SQL> col path for a50
SQL> select group_number, disk_number, name, path, failgroup, mode_status, voting_file from v$asm_disk order by 1, 2;
GROUP_NUMBER DISK_NUMBER NAME PATH FAILGROUP MODE_STATUS VO
------------ ----------- ------------------------------ ----------------------- -------------------- -------------- --
1 0 CRS_0000 /dev/CELL01-crs1 CRS_0000 ONLINE Y
1 1 CRS_0001 /dev/CELL02-crs2 CRS_0001 ONLINE Y
1 2 CRS_0002 /dev/CELL03-crs3 CRS_0002 ONLINE Y
2 0 DATA_0000 /dev/CELL03-data1 CELL03 ONLINE N
2 1 DATA_0001 /dev/CELL03-data2 CELL03 ONLINE N
2 2 DATA_0002 /dev/CELL02-data1 CELL02 ONLINE N
2 3 DATA_0003 /dev/CELL02-data2 CELL02 ONLINE N
2 4 DATA_0004 /dev/CELL01-data1 CELL01 ONLINE N
2 5 DATA_0005 /dev/CELL01-data2 CELL01 ONLINE N
9 rows selected.
SQL> select group_number, name, total_mb, free_mb, USABLE_FILE_MB, offline_disks, state, type from v$asm_diskgroup;
GROUP_NUMBER NAME TOTAL_MB FREE_MB USABLE_FILE_MB OFFLINE_DISKS STATE TYPE
------------ ------------------------------ ---------- ---------- -------------- ------------- ---------------------- ----------
1 CRS 3000 2033 516 0 MOUNTED NORMAL
2 DATA 61440 56012 17766 0 MOUNTED NORMAL
说明：一般我会将磁盘组的兼容性参数设置为11.2，如有特殊需求，还可以设置disk_repair_time（默认3.6h）。
SQL> col COMPATIBILITY for a30
SQL> col DATABASE_COMPATIBILITY for a30
SQL> select NAME, COMPATIBILITY, DATABASE_COMPATIBILITY from v$asm_diskgroup;
NAME COMPATIBILITY DATABASE_COMPATIBILITY
------------------------------ ------------------------------ ------------------------------
CRS 11.2.0.0.0 11.2.0.0.0
DATA 11.2.0.0.0 11.2.0.0.0
--设置DATA磁盘组disk_repair_time(可理解为磁盘离线删除的时间)属性为4.5h
SQL> ALTER DISKGROUP data SET ATTRIBUTE 'disk_repair_time' = '4.5h';
Diskgroup altered.