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Remove ioctl failed: Device or resource busy – How to resolve

by | Jun 28, 2021

Stuck with Remove ioctl failed: Device or resource busy error? We can help you.

As part of our Server Management Services, we assist our customers with several such queries.

Today, let us see how to resolve this error.


Remove ioctl failed: Device or resource busy


Let us go through the steps followed by our Support Techs to find the process preventing the dm entry from removed:

1.Firstly, SSH into HV shown in the error log.

2.Then, check the device mapper hierarchy to see which backup is utilizing the -real snapshot in the error log.

Run the below command:

dmsetup ls –tree | grep -B5 onapp–xxxxxxxxxxxxxx-zzzzzzzzzzzzzz-real

Please note if you don’t see the root backup device, you may need to increase the value for the -B switch to something higher than 5.

3.Then, determine what process is using the top dm entry in the hierarchy with lsof.


Run the below command:

lsof /dev/onapp-xxxxxxxxxxxxxx/backup-yyyyyyyyyyyyyy

4.Since the backup is being utilized by tgtd, check if there are any iSCSI targets active.

Run the below command:

tgtadm –lld iscsi –mode target –op show

5.Then, check the Backup Server for related ISCSI sessions and logout of them.

  • Login to the backup server shown under “ACL information” from the previous step and run iscsiadm -m session.
  • Compare the target name from the previous step and logout of the corresponding ISCSI sessions using iscsiadm -m node -u -T <target name>.
  • If there are no corresponding sessions on the backup server, you can skip to step 6.

Make sure the -T command is -T. If the iscsiadm command does not receive the -T after the -u, it will logout of all iscsi targets.

6.Delete the iSCSI target.

  • Go back to the Hypervisor and run tgtadm –lld iscsi –op delete –mode target –tid *
  • tid stands for Target ID, which is shown when running the command in step 4.

7.Finally, remove the dm entries for the backup and the -real snapshot.

For entries that end with X1, you should run this first:

kpartx -d -p X /dev/mapper/backup-XXXXXXXXXX

Then, run the below commands:

dmsetup remove /dev/onapp-xxxxxxxxxxxxxx/backup-yyyyyyyyyyyyyy
dmsetup remove /dev/onapp-xxxxxxxxxxxxxx/backup-yyyyyyyyyyyyyy-cow
dmsetup remove /dev/mapper/onapp–xxxxxxxxxxxxxx-zzzzzzzzzzzzzz-real


[Need any further help? Feel free to contact us anytime]



In short, we saw steps followed by our Support Techs to find the process preventing the dm entry from removed


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