近日遇到一个问题，就是ASMdiskgroup无法挂载，通过分析之后，发现有会快存在，但是由于没有备份，没有办法重建diskgroup并从backup恢复--所以所以所以....备份
近日遇到一个问题，就是ASM diskgroup无法挂载，通过分析之后，发现有会快存在，，但是由于没有备份，没有办法重建diskgroup并从backup恢复--所以所以所以....备份很重要啊！不然，哭！！是早晚的事情！
通过解决这个问题，我在自己的测试环境测试了如何在ASM diskgroup无法mount的情况下，尽量挽救数据文件。
这里使用到oracle 工具AMDU，该具体信息可以参考AMDU functionality and usage (Doc ID 855791.1)
1. 由于diskgroup无法挂载，SPFILE、CONTROLFILE、DATAFILE都无法读取
根据步骤，我们首先需要恢复spfile文件，spfile文件存在的意义就是找到control_files的位置，如果spfile无法访问，需要查找备份。
SQL> show parameter control_files +DATA/db/controlfile/current.260.804295233, +FRA/db/controlfile/current.256.804295237
2. 通过ASM实例找到asm_diskstring
SQL> show parameter disk NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ asm_diskgroups string DATA, FRA asm_diskstring string /dev/sd*
3. 查找asm disk的路径，后续要指定diskstring来扫描磁盘
SQL> select NAME,STATE,TYPE,OFFLINE_DISKS,VOTING_FILES from v$asm_diskgroup; SQL> col PATH for a50 SQL> col name for a10 SQL> set line 200 SQL> select DISK_NUMBER,GROUP_NUMBER,PATH,name from v$asm_disk; DISK_NUMBER GROUP_NUMBER PATH NAME ----------- ------------ -------------------------------------------------- ---------- 1 2 /dev/oracleasm/disks/ASMDISK5 FRA_0001 0 2 /dev/oracleasm/disks/ASMDISK4 FRA_0000 2 1 /dev/oracleasm/disks/ASMDISK3 DATA_0002 DISK_NUMBER GROUP_NUMBER PATH NAME ----------- ------------ -------------------------------------------------- ---------- 1 1 /dev/oracleasm/disks/ASMDISK2 DATA_0001 0 1 /dev/oracleasm/disks/ASMDISK1 DATA_0000
4. 在diskgroup mount状态，是不能使用amdu导出文件的
执行amdu命令开始导出，遇到错误
$ amdu -diskstring '/dev/oracleasm/disks/ASMDISK*' -extract data.260 amdu_2013_07_03_17_29_13/ AMDU-00204: Disk N0005 is in currently mounted diskgroup DATA AMDU-00201: Disk N0005: '/dev/oracleasm/disks/ASMDISK1'
检查发现磁盘组mount
$ crsctl status res -t -------------------------------------------------------------------------------- NAME TARGET STATE SERVER STATE_DETAILS -------------------------------------------------------------------------------- ora.DATA.dg ONLINE ONLINE single-db ora.FRA.dg ONLINE ONLINE single-db
5. 导出控制文件
$ amdu -diskstring '/dev/oracleasm/disks/ASMDISK*' -extract data.260 amdu_2013_07_03_17_46_07/ [oracle@Single-DB amdu]$ cd amdu_2013_07_03_17_46_07/ [oracle@Single-DB amdu_2013_07_03_17_46_07]$ ls DATA_260.f report.txt
6. 尝试挂载control file
发现spfile也存放在磁盘组中无法nomount
$ sqlplus / as sysdba SQL> startup nomount; ORA-01078: failure in processing system parameters ORA-01565: error in identifying file '+DATA/db/spfiledb.ora' ORA-17503: ksfdopn:2 Failed to open file +DATA/db/spfiledb.ora ORA-15056: additional error message ORA-17503: ksfdopn:DGOpenFile05 Failed to open file +DATA/db/spfiledb.ora ORA-17503: ksfdopn:2 Failed to open file +DATA/db/spfiledb.ora ORA-15001: diskgroup "DATA" does not exist or is not mounted ORA-06512: at line 4
7. 那就编辑一个新的pfile文件
$ cp init.ora spfilebk.ora $ vi spfilebk.ora ~~~~~~~~~~~~~~~ db_name='DB' sga_target=1G processes = 150 audit_trail ='db' db_block_size=8192 db_domain='' db_recovery_file_dest_size=2G open_cursors=300 remote_login_passwordfile='EXCLUSIVE' undo_tablespace='UNDOTBS1' control_files = /u01/amdu/amdu_2013_07_03_17_46_07/DATA_260.f compatible ='11.2.0' ~~~~~~~~~~~~~~~
8. 通过导出的控制文件启动数据库到mount模式，成功启动，说明AMDU导出的数据时正确的，继续。。。。。
$ sqlplus / as sysdba SQL> startup nomount pfile='/u01/app/oracle/product/11.2.0/dbhome_1/dbs/spfilebk.ora'; ORACLE instance started. Total System Global Area 1068937216 bytes Fixed Size 2220200 bytes Variable Size 281022296 bytes Database Buffers 780140544 bytes Redo Buffers 5554176 bytes SQL> alter database mount; Database altered.
9. 查看数据文件的位置，然后一一导出
SQL> select name from v$datafile; NAME -------------------------------------------------------------------------------- +DATA/db/datafile/system.256.804295135 +DATA/db/datafile/sysaux.257.804295137 +DATA/db/datafile/undotbs1.258.804295139 +DATA/db/datafile/users.259.804295141 $ amdu -diskstring '/dev/oracleasm/disks/ASMDISK*' -extract data.256
10. 重命名数据文件，并移动到同一个目录下，准备挂载数据文件
$ mv amdu_2013_07_03_18_12_56/DATA_257.f sysaux.257.804295137 $ mv amdu_2013_07_03_18_22_23/DATA_259.f users.259.804295141 $ mv amdu_2013_07_03_18_23_06/DATA_258.f undotbs1.258.804295139 $ ll -rw-r--r-- 1 oracle dba 545267712 Jul 3 18:14 sysaux.257.804295137 -rw-r--r-- 1 oracle dba 702554112 Jul 3 18:11 system.256.804295135 -rw-r--r-- 1 oracle dba 99622912 Jul 3 18:23 undotbs1.258.804295139 -rw-r--r-- 1 oracle dba 5251072 Jul 3 18:22 users.259.804295141
11. 挂载前需要修改pfile文件，下面是open数据库是control file如何识别不同路径的datafile， 我使用convert参数来解决（也可以是用set newname的方式）
db_file_name_convert='+DATA/db/datafile','/u01/amdu/amdu_datafile'
添加完pfile，启动数据库，最终成功启动数据库
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