ORA-15020: discovered duplicate ASM disk
Wanted to create an ASM diskgroup. I was testing something and forgot to change asm_diskstring parameter. I created few links in /dev/rdsk, which were pointing to the disks .
ASM_DISKSTRING had both, original diskname and links, for the discovery.
SQL> show parameter string
NAME TYPE VALUE
———————————— ———– ——————————
asm_diskstring string /dev/rdsk/c*, /dev/rdsk/disk*
/dev/rdsk/disk1 was pointing to c4t50060E800564F774d14s6
/dev/rdsk/disk2 was pointing to c4t50060E800564F774d15s6
But when I tried creating the diskgroup by using the linked name, ASM error out giving following message
SQL> create diskgroup dg1 external redundancy disk ‘/dev/rdsk/disk1’, ‘/dev/rdsk/disk2’
create diskgroup dg1 external redundancy disk ‘/dev/rdsk/disk1’, ‘/dev/rdsk/disk2’
ERROR at line 1:
ORA-15018: diskgroup cannot be created
ORA-15020: discovered duplicate ASM disk “dg1_0000”
ASM is intelligent enough to understand duplicate disks and point out error.