ORA-15042: ASM disk "1" is missing from group number "1" in KVM guest.txt

Error:
ERROR: diskgroup DB_DATA was not mounted
ORA-15032: not all alterations performed
ORA-15040: diskgroup is incomplete
ORA-15042: ASM disk "1" is missing from group number "1"

Solution:
Please perform the following checks in case if you are facing problem while mounting the disk group.
• Check the Virt disk size and that should be same as the size of Physical disk provision from Host. Please rescan the iscsi bus in case if disk size mismatch.
o Get the Bus ID from multipath -ll output corresponding to the disk and run the below command for all ISCSI bus –
echo 1 > /sys/class/scsi_device/7\:0\:1\:22/device/rescan
echo 1 > /sys/class/scsi_device/7\:0\:3\:22/device/rescan
echo 1 > /sys/class/scsi_device/9\:0\:3\:22/device/rescan
echo 1 > /sys/class/scsi_device/9\:0\:1\:22/device/rescan
echo 1 > /sys/class/scsi_device/7\:0\:1\:2/device/rescan
echo 1 > /sys/class/scsi_device/7\:0\:3\:2/device/rescan
echo 1 > /sys/class/scsi_device/9\:0\:3\:2/device/rescan
echo 1 > /sys/class/scsi_device/9\:0\:1\:2/device/rescan
The Disk is mapped do a different device Name even after above given Procedure.

[root@DBServer ~]# ls -ltr /dev/disk/by-id/scsi-36*43
lrwxrwxrwx 1 root root 10 Oct  5 14:01 /dev/disk/by-id/scsi-36000d31000458a000000000000000143 -> ../../sdfl

36000d31000458a000000000000000054 dm-26 COMPELNT,Compellent Vol
size=10G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
  |- 7:0:1:2  sdac 65:192  active ready running
  |- 9:0:1:2  sdbt 68:112  active ready running
  |- 7:0:3:2  sddv 71:208  active ready running
  `- 9:0:3:2  sdfl 130:112 active ready running


  36000d31000458a000000000000000143 dm-34 COMPELNT,Compellent Vol
size=1.0T features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
  |- 7:0:1:22 sdas 66:192  active ready running
  |- 9:0:1:22 sdci 69:96   active ready running
  |- 7:0:3:22 sdel 128:208 active ready running
  `- 9:0:3:22 sdfv 131:16  active ready running

  So,  scsi-36000d31000458a000000000000000143 has to point to /sdfv. Now do a
  [root@DBServer ~]# udevadm trigger

After that Please check the output.

[root@DBServer ~]# ls -ltr /dev/disk/by-id/scsi-36*43
lrwxrwxrwx 1 root root 10 Dec 21 16:02 /dev/disk/by-id/scsi-36000d31000458a000000000000000143 -> ../../sdfv

• Ensure that all Virt disk mapped on VM box belongs to correct disk group, for that please run the below command and check the diskgroup name.
o kfed read dev=/dev/vdb | grep -i grpname
• If you find any disk which doesn’t belongs to DB diskgroup then please unmap and map the correct disk from VM console.