How to detach cinder volume

Lee Yarwood lyarwood at
Wed Mar 17 10:29:38 UTC 2021

On Mon, 15 Mar 2021 at 15:38, Md. Hejbul Tawhid MUNNA
<munnaeebd at> wrote:
> Hi,
> We are using openstack rocky.
> One of our openstack vm was running with 3 volume ,  1 is bootable and another 2 is normal volume . We have deleted 1 normal volume without properly detaching.
> So volume is deleted but instance is still showing 3 volume is attached. Now we can't snapshot the instance and facing some others issue.
> Please advise how we can detach the volume(deleted) from the instance
> Note: We have reset state volume attached status to detached and delete the volume.

Ewww I wish we made this harder. Please try to avoid resetting states
like this unless you really have to.

The cleanest way of detaching the volume from the instance is going to
be to mark the volume attachment as deleted within the Nova database
and hard rebooting the instance.

$ mysql nova_cell1
MariaDB [nova_cell1]> update block_device_mapping set deleted = id
where volume_id = '$volume_id' and instance_uuid = '$instance_uuid';

Confirm the volume is no longer listed as attached and then hard reboot:

$ openstack server volume list $instance
$ openstack server reboot --hard $instance

Depending on your volume backend you will likely need to manually
clean up any now stale volume connections on the host. For example,
deleting any mpath devices etc. You might want to consider a full
compute host reboot to ensure things are clean.

Anyway, hope this helps,


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