Oracleasm deletedisk failed Unable to clear disk
First of all, I checked that there were no extents on DISK1.

$ . oraenv
ORACLE_SID = [+ASM1] ?

SQL&gt; select PXN_KFFXP,  -- physical extent number
           XNUM_KFFXP, -- virtual extent number
           DISK_KFFXP, -- disk number
           AU_KFFXP    -- allocation unit number
    from X$KFFXP
    where DISK_KFFXP=1;

no rows selected


I cleared the disk header by dd:

# dd if=/dev/zero of=/dev/oracleasm/disks/DISK1 bs=1024 count=100
100+0 records in
100+0 records out
102400 bytes (102 kB) copied, 0.000156 seconds, 656 MB/s


Note: My allocation unit is 1MB that is why I am using bs=1024.

Then deleted disk by oracleasm:

# oracleasm deletedisk DISK1
# oracleasm scandisks    &lt;--Do this step on all nodes


To tell the truth it is not a good way to solve the problem, because when I run the following command on the second node:

/sbin/blkid | grep oracleasm

/dev/sdg1: LABEL="DISK6" TYPE="oracleasm"
/dev/sdb1: LABEL="DISK1" TYPE="oracleasm"
/dev/sdh2: LABEL="DISK8" TYPE="oracleasm"
/dev/sdh3: LABEL="DISK9" TYPE="oracleasm"
/dev/sdh4: LABEL="DISK10" TYPE="oracleasm"
/dev/sdh1: LABEL="DISK7" TYPE="oracleasm"
/dev/sdi1: LABEL="DISK11" TYPE="oracleasm"
/dev/sdi2: LABEL="DISK12" TYPE="oracleasm"


It shows me the label DISK1.

So clearing the ASM disk header using dd left some junks.