[openstack-dev] [nova] New image backend: StorPool

Matt Riedemann mriedemos at gmail.com
Fri Mar 16 16:00:21 UTC 2018

On 3/16/2018 10:33 AM, Peter Penchev wrote:
> Would there be any major opposition to adding a StorPool shared
> storage image backend, so that our customers are not limited to
> volume-backed instances?  Right now, creating a StorPool volume and
> snapshot from a Glance image and then booting instances from that
> snapshot works great, but in some cases, including some provisioning
> and accounting systems on top of OpenStack, it would be preferable to
> go the Nova way and let the hypervisor think that it has a local(ish)
> image to work with, even though it's on shared storage anyway.  This
> will go hand-in-hand with our planned Glance image driver, so that
> creating a new instance from a Glance image would happen
> instantaneously (create a StorPool volume from the StorPool snapshot
> corresponding to the Glance image).

Ask the EMC ScaleIO team how well this has gone for them:


There has been a lot of discussion about a generic Cinder image backend 
driver in nova so that we don't need to have the same storage backend 
driver explosion that Cinder has, and we could also then replace the 
nova lvm/rbd image backends and just use Cinder volumes for 
volume-backed instances.

I could find lots of discussion references about this, but basically no 
one is planning to step up to work on that, and the existing libvirt 
imagebackend code is a mess, so piling more backends into the mix isn't 
very attractive.

Anyway, just FYI on all of that history.

> If this will help the decision, we do have plans for adding a
> full-blown Nova third-party CI in the near future, so that both our
> volume attachment driver, this driver, and our upcoming Glance image
> driver will see some more testing.

3rd party CI would be a requirement to get it added anyway, it's not 
really an option.




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