I think I'm getting closer. It seems the snapshot of the VM did not get deleted and that might be the problem. Can someone give me a hint how to remove the snapshot as I get an error: Cannot remove Snapshot. The following disks are in ILLEGAL status: uyuni-OS-Disk1 - please remove them and try again. Yet, removal of the disk cannot happen as I got: Cannot detach Virtual Disk. The disk is already configured in a  snapshot. In order to detach it, remove the disk's  snapshot. This seems like 'Catch 22' . Best Regards, Strahil Nikolov On Jul 7, 2019 17:30, Strahil <hunter86_bg(a)yahoo.com&gt; wrote: > > Hello All, > > I have changed  my system layout and the old disk is removed (echo 1 > /sys/block/sdX/device/delete)  from OS, but UI complains when I try to remove  with the following error: > > Error while executing action:  Cannot remove  Virtual Disk. At least one of the VMs is not down. > > Is it a limitation of oVirt ? If so, I will open an enhancement entry in bugzilla. > > As far as  I remember KVM allowed me to make such stuff  without any issues so far. > > Best Regards, > Strahil Nikolov