After Re-Creating the ASM Instance, Old Diskgroup Information Remains (文档 ID 266078.1)

APPLIES TO:

Oracle Server - Enterprise Edition - Version: 10.1
This problem can occur on any platform.

SYMPTOMS

Following the removal and re-creation of an ASM instance, you may see old data left behind from the old ASM instance. 

ie

ls -l /dev/rdsk/osm*
-rw-rw-rwT 1 qatest g527 524288000 Jul 31 12:03 /dev/rdsk/osm1
-rw-rw-rwT 1 qatest g527 524288000 Jul 31 12:04 /dev/rdsk/osm2

You may also be unable to create an ASM diskgroup with the same name as an old diskgroup and may receive the following errors:

ORA-15018: diskgroup cannot be created
ORA-15033: disk '/dev/rdsk/osm2' belongs to diskgroup "DATA"
ORA-15033: disk '/dev/rdsk/osm1' belongs to diskgroup "DATA"

CAUSE

ASM Metadata has been left behind on the disk.

SOLUTION

To resolve this problem, remove the old ASM instance from the /etc/oratab file or /var/opt/oracle/oratab file, depending on your platform and use dd to clear out the first 1000 blocks of the ASM disk(s). 

Example: 

dd if=/dev/zero of=/dev/rdsk/osm1 bs=8192 count=1000 
dd if=/dev/zero of=/dev/rdsk/osm2 bs=8192 count=1000

Care should be taken when using dd as this can overwrite datafiles that are in use with no warning.

Once you have done this, re-create your ASM instance and you should no longer see the old diskgroup information.

REFERENCES