[openstack-dev] [cinder] [nova] Problem of Volume(in-use) Live Migration with ceph backend

Boxiang Zhu bxzhu_5355 at 163.com
Fri Oct 19 15:21:01 UTC 2018

Hi melanie, thanks for your reply.

The version of my cinder and nova is Rocky. The scope of the cinder spec[1] 
is only for available volume migration between two pools from the same ceph cluster.
If the volume is in-use status[2], it will call the generic migration function. So that as you 
describe it, on the nova side, it raises NotImplementedError(_("Swap only supports host devices"). 
The get_config of net volume[3] has not source_path.

So does anyone try to succeed to migrate volume(in-use) with ceph backend or is anyone doing something of it?

[1] https://review.openstack.org/#/c/296150
[2] https://review.openstack.org/#/c/256091/23/cinder/volume/drivers/rbd.py
[3] https://github.com/openstack/nova/blob/stable/rocky/nova/virt/libvirt/volume/net.py#L101

On 10/19/2018 22:39,melanie witt<melwittt at gmail.com> wrote:
On Fri, 19 Oct 2018 11:33:52 +0800 (GMT+08:00), Boxiang Zhu wrote:
When I use the LVM backend to create the volume, then attach it to a vm.
I can migrate the volume(in-use) from one host to another. The nova
libvirt will call the 'rebase' to finish it. But if using ceph backend,
it raises exception 'Swap only supports host devices'. So now it does
not support to migrate volume(in-use). Does anyone do this work now? Or
Is there any way to let me migrate volume(in-use) with ceph backend?

What version of cinder and nova are you using?

I found this question/answer on ask.openstack.org:


and it looks like there was some work done on the cinder side [1] to
enable migration of in-use volumes with ceph semi-recently (Queens).

On the nova side, the code looks for the source_path in the volume
config, and if there is not one present, it raises
NotImplementedError(_("Swap only supports host devices"). So in your
environment, the volume configs must be missing a source_path.

If you are using at least Queens version, then there must be something
additional missing that we would need to do to make the migration work.

[1] https://blueprints.launchpad.net/cinder/+spec/ceph-volume-migrate


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