[root@Hostname ~]# /etc/init.d/oracleasm createdisk DATA_0001 /dev/sdb2
Marking disk "DATA_0001" as an ASM disk: [FAILED]
[root@Hostname ~]# tail -F /var/log/oracleasm
Reloading disk partitions: done
Cleaning any stale ASM disks...
Validating disk "DATA_0001"
Scanning system for ASM disks...
Disk "DATA_0001" is a valid ASM disk
Device "/dev/sdb2" is already labeled for ASM disk "DATA_0001"
Solution:
[root@stagedevdb2 ~]# /etc/init.d/oracleasm deletedisk DATA_0001
Removing ASM disk "DATA_0001": [ OK ]
[root@stagedevdb2 ~]# /etc/init.d/oracleasm createdisk DATA_0001 /dev/sdb2
Marking disk "DATA_0001" as an ASM disk: [ OK ]