APPLIES TO:
Oracle Database - Enterprise Edition - Version 11.1.0.6 to 11.2.0.4 [Release 11.1 to 11.2]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Generic (Platform Independent)
GOAL
How to resotore the database from AMDU after Disk corruption ?
SOLUTION
NOTE:This is not a replacement for RMAN backups to restore the contents of corrupted ASM diskgroups (which is supported). This procedure is at best 'best effort' and not supported! Because with this method we may not be able to restore the database completely.
1. Create pfile of lost database , from database alert.log startup messages.
2. Startup database in nomount
3. Get the controlfile number from db alert log , it will show while starting the database here in this eg. its 256
eg., control_files='+<DGNAME>/<DB_NAME>/controlfile/current.256.709676643'
If you have controlfile backup already in non-asm location edit the pfile to point to location of non-asm and then mount the database
If you dont have controlfile backup then go to step 4 after determining the file# from step 3
4. $ amdu -diskstring <asm_diskstring> -extract <DGNAME>.256
5. shutdown the database and change the control_file location to point to the extracted file location
6. startup mount the database
7. once mounted, get the datafile file numbers using "select name from v$datafile"
And get online redo logfile from "select * from v$logfile".
8. Extract all datafiles and redolog files in similar manner
9. alter database rename <datafile 1> to < newly extracted location>
10. open the database
