On 21/01, Nir Soffer wrote:
> On Thu, Jan 21, 2021 at 8:50 AM Konstantin Shalygin <k0ste@k0ste.ru> wrote:
> >
> > I understood, more than the code that works with qemu already exists for openstack integration
>
> We have code on vdsm and engine to support librbd, but using in cinderlib
> based volume is not a trivial change.
>
> On engine side, this means changing the flow, so instead of attaching
> a device to a host, engine will configure the xml with network disk, using
> the rbd url, same way as old cinder support was using.
>
> To make this work, engine needs to configure the ceph authentication
> secrets on all hosts in the DC. We have code to do this for old cinder storage
> doman, but it is not used for new cinderlib setup. I'm not sure how easy is to
> use the same mechanism for cinderlib.

Hi,

All the data is in the connection info (including the keyring), so it
should be possible to implement.

>
> Generally, we don't want to spend time on special code for ceph, and prefer
> to outsource this to os brick and the kernel, so we have a uniform way to
> use volumes. But if the special code gives important benefits, we can
> consider it.
>

I think think that's reasonable. Having less code to worry about and
making the project's code base more readable and maintainable is a
considerable benefit that should not be underestimated.


> I think openshift virtualization is using the same solution (kernel based rbd)
> for ceph. An important requirement for us is having an easy way to migrate
> vms from ovirt to openshift virtuations. Using the same ceph configuration
> can make this migration easier.
>

The Ceph CSI plugin seems to have the possibility of using krbd and
rbd-nbd [1], but that's something we can also achieve in oVirt by adding
back the rbd-nbd support in cinderlib without changes to oVirt.

Cheers,
Gorka.

[1]: https://github.com/ceph/ceph-csi/blob/04644c1d5896b493d6aaf9ab66f2302cf67a2ee3/internal/rbd/rbd_attach.go#L35-L41

> I'm also not sure about the future of librbd support in qemu. I know that
> qemu folks also want to get rid of such code. For example libgfapi
> (Glsuter native driver) is not maintained and likely to be removed soon.
>
> If this feature is important to you, please open RFE for this, and explain why
> it is needed.
>
> We can consider it for future 4.4.z release.
>
> Adding some storage and qemu folks to get more info on this.
>
> Nir
>
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