[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  ]