How To Drop and Recreate ASM Diskgroup
(Doc ID 563048.1)
Last updated on JANUARY 24, 2020
Applies to:Oracle Database - Standard Edition - Version 10.2.0.2 to 184.108.40.206 [Release 10.2 to 11.2]
Oracle Database - Enterprise Edition - Version 10.2.0.2 to 220.127.116.11 [Release 10.2 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
Generic (Platform Independent)
***Checked for relevance on 27-Feb-2011***
This article describe how we can drop and recreate ASM diskgroup when its not possible to perform this through SQL command.
When a member disk in external redundancy diskgroup is no longer present (or destroyed beyond repair) and you want to drop the diskgroup completely and recreate it or add the disks of the diskgroup to other diskgroups. The diskgroup can not be mounted, because one of the disks is missing, hence the "drop diskgroup" command will not work.
In 10g you can use a workaround by erasing the header of the disk using the dd command.
In 11g, the diskgroup can be dropped when its dismounted with FORCE option especially for normal and high redundancy diskgroups:
Administering ASM Disk Groups
Dropping Disk Groups
Erasing the header using "dd" command is very dangerous operation and need to be done under support supervision and when it confirmed by support that fixing the header is impossible.
In all cases and before the erasing operation you should gather the following information:
1. alert.log file from all ASM instances going back to last successful mount for diskgroup.
2. OS logs.
3. Backup disk header for all member disks in diskgroup:
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