Comment 6 for bug 1335889

The work-around of allowing to delete volume attached to an already-deleted VM is successful as below:

xtrutri@ubuntu:~/Work/devstack-stable-juno$ cinder list
+--------------------------------------+--------+--------------+------+-------------+----------+--------------------------------------+
| ID | Status | Display Name | Size | Volume Type | Bootable | Attached to |
+--------------------------------------+--------+--------------+------+-------------+----------+--------------------------------------+
| 5fc4746e-bc31-4764-8877-cf32de9b4e22 | in-use | new_vol | 1 | lvmdriver-1 | false | 8e6033c7-1450-4526-95c1-84879a51af5e |
+--------------------------------------+--------+--------------+------+-------------+----------+--------------------------------------+

xtrutri@ubuntu:~/Work/devstack-stable-juno$ cinder delete 5fc4746e-bc31-4764-8877-cf32de9b4e22

We can see that now it's possible to delete the volume whose status is still "in-use"

Please be noted the Cinder's detaching of the associated volume, which is triggered by Nova's deleting of a VM, is temporarily disabled for having the scenario that the volume is attached to an already-deleted VM