当ASM磁盘组无法MOUNT之时如何找到对应的物理磁盘？

如果数据存放于ASM磁盘组之上，当ASM磁盘组无法MOUNT起来，则意味着无法打开数据库。我们假设磁盘头部没有损坏，只是盘符变了，但无法正确设置ASM_DISKSTRING参数。

实验环境： RHEL5 + ORACLE10.2.0.4RAC+RAW+ASM

通过此次实验你将掌握以下知识点：

1. 初步了解如何使用ORACLE两款内部工具amdu/kfed

2. 在ASM磁盘组无法MOUNT的情况下，如何对应物理磁盘和ASMDISK的关系

3. 当ASM_DISKSTRING设置不全时，如何补全并将磁盘组MOUNT起来。

SQL> ALTER DISKGROUP ALL MOUNT

Sat Nov 29 22:15:09 2014

NOTE: cache registered group DATA number=1 incarn=0x5bc84523

Sat Nov 29 22:15:09 2014

NOTE: Hbeat: instance first (grp 1)

Sat Nov 29 22:15:13 2014

NOTE: start heartbeating (grp 1)

NOTE: cache opening disk 0 of grp 1: DATA_0000 path:/dev/raw/raw3 <<<<<<<

Sat Nov 29 22:15:13 2014

NOTE: F1X0 found on disk 0 fcn 0.619

NOTE: cache opening disk 1 of grp 1: DATA_0001 path:/dev/raw/raw4 <<<<<<<

NOTE: cache mounting (first) group 1/0x5BC84523 (DATA)

* allocate domain 1, invalid = TRUE

Sat Nov 29 22:15:13 2014

NOTE: attached to recovery domain 1

Sat Nov 29 22:15:13 2014

NOTE: starting recovery of thread=1 ckpt=23.573 group=1

NOTE: advancing ckpt for thread=1 ckpt=23.573

NOTE: cache recovered group 1 to fcn 0.5267

Sat Nov 29 22:15:13 2014

NOTE: opening chunk 1 at fcn 0.5267 ABA

NOTE: seq=24 blk=574

Sat Nov 29 22:15:13 2014

NOTE: cache mounting group 1/0x5BC84523 (DATA) succeeded

SUCCESS: diskgroup DATA was mounted

下面我们取消raw3,raw4裸设备的定义，重启操作系统...

SQL> alter diskgroup all mount;

alter diskgroup all mount

*

ERROR at line 1:

ORA-15032: not all alterations performed

ORA-15063: ASM discovered an insufficient number of disks for diskgroup "DATA"

SQL> alter system set asm_diskstring='/dev/sdd1'; <<<<<此处只添加一块盘符

System altered.

SQL> alter diskgroup data mount;

alter diskgroup data mount

*

ERROR at line 1:

ORA-15032: not all alterations performed

ORA-15040: diskgroup is incomplete

ORA-15042: ASM disk "1" is missing <<<<<<依旧缺失一块盘符

[oracle@dwdb1 tmp]$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:`pwd`

[oracle@dwdb1 tmp]$ ./amdu -diskstring='/dev/sd*'
-dump 'DATA' <<<<<扫描/dev/sd*所有设备

[oracle@dwdb1 tmp]$ cd amdu_2014_11_30_08_28_26

[oracle@dwdb1 amdu_2014_11_30_08_28_26]$ ls -lrt

total 94364

-rw-r--r-- 1 oracle oinstall 7231 Nov 30 08:28 report.txt

-rw-r--r-- 1 oracle oinstall 8000 Nov 30 08:28 DATA.map

-rw-r--r-- 1 oracle oinstall 96514048 Nov 30 08:28 DATA_0001.img

截取部分report.txt内容:

----------------------------- DISK REPORT N0010 ------------------------------

Disk Path: /dev/sdd1

Unique Disk ID:

Disk Label:

Physical Sector Size: 512 bytes

Disk Size: 1019 megabytes

Group Name: DATA

Disk Name: DATA_0000

Failure Group Name: DATA_0000

Disk Number: 0

Header Status: 3

Disk Creation Time: 2014/11/05 12:55:10.506000

Last Mount Time: 2014/11/29 23:14:47.663000

Compatibility Version: 0x0a100000

Disk Sector Size: 512 bytes

Disk size in AUs: 1019 AUs

Group Redundancy: 1

Metadata Block Size: 4096 bytes

AU Size: 1048576 bytes

Stride: 113792 AUs

Group Creation Time: 2014/11/05 12:55:10.486000

File 1 Block 1 location: AU 2

----------------------------- DISK REPORT N0012 ------------------------------

Disk Path: /dev/sde1 <<<<<<<<<<<<<<<<<磁盘全路径

Unique Disk ID:

Disk Label:

Physical Sector Size: 512 bytes

Disk Size: 1019 megabytes

Group Name: DATA

Disk Name: DATA_0001

Failure Group Name: DATA_0001

Disk Number: 1 <<<<<<<<<<<<<<<<<<<<<<<<<磁盘序号为1

Header Status: 3

Disk Creation Time: 2014/11/05 13:01:56.714000

Last Mount Time: 2014/11/29 23:14:47.663000

Compatibility Version: 0x0a100000

Disk Sector Size: 512 bytes

Disk size in AUs: 1019 AUs

Group Redundancy: 1

Metadata Block Size: 4096 bytes

AU Size: 1048576 bytes

Stride: 113792 AUs

Group Creation Time: 2014/11/05 12:55:10.486000

File 1 Block 1 location: AU 0

...

------------------------- SUMMARY FOR DISKGROUP DATA -------------------------

Allocated AU's: 1632

Free AU's: 406

AU's read for dump: 100

Block images saved: 23563

Map lines written: 100

Heartbeats seen: 0

Corrupt metadata blocks: 0

Corrupt AT blocks: 0

******************************* END OF REPORT ********************************

结合以上信息，使用KFED再次确认：

[oracle@dwdb1 tmp]$ kfed read /dev/sde1 |more

kfbh.endian: 1 ; 0x000: 0x01

kfbh.hard: 130 ; 0x001: 0x82

kfbh.type: 1 ; 0x002: KFBTYP_DISKHEAD

kfbh.datfmt: 1 ; 0x003: 0x01

kfbh.block.blk: 0 ; 0x004: T=0 NUMB=0x0

kfbh.block.obj: 2147483649 ; 0x008: TYPE=0x8 NUMB=0x1

kfbh.check: 1289251580 ; 0x00c: 0x4cd86afc

kfbh.fcn.base: 0 ; 0x010: 0x00000000

kfbh.fcn.wrap: 0 ; 0x014: 0x00000000

kfbh.spare1: 0 ; 0x018: 0x00000000

kfbh.spare2: 0 ; 0x01c: 0x00000000

kfdhdb.driver.provstr: ORCLDISK ; 0x000: length=8

kfdhdb.driver.reserved[0]: 0 ; 0x008: 0x00000000

kfdhdb.driver.reserved[1]: 0 ; 0x00c: 0x00000000

kfdhdb.driver.reserved[2]: 0 ; 0x010: 0x00000000

kfdhdb.driver.reserved[3]: 0 ; 0x014: 0x00000000

kfdhdb.driver.reserved[4]: 0 ; 0x018: 0x00000000

kfdhdb.driver.reserved[5]: 0 ; 0x01c: 0x00000000

kfdhdb.compat: 168820736 ; 0x020: 0x0a100000

kfdhdb.dsknum: 1 ; 0x024: 0x0001

kfdhdb.grptyp: 1 ; 0x026: KFDGTP_EXTERNAL

kfdhdb.hdrsts: 3 ; 0x027: KFDHDR_MEMBER

这样,就可以确定disk1就为/dev/sde1了

SQL> alter system set asm_diskstring='/dev/sdd1','/dev/sde1';

System altered.

SQL> alter diskgroup data mount;

Diskgroup altered.

接下来就可以启动数据库了。

以上简单地使用了AMDU/KFED命令，这两款具都可以实现在ASM磁盘组无法MOUNT的情况下对磁盘读写，其中KFED命令还可以用于磁盘头部的修复(10.2.5.0以上的数据库全有自动备份)，还可以做异常恢复：从ASM磁盘直接恢复数据文件，总之也是个非常强大的工具。

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