Libvirt volumes are copied in case of block live migration

[Thomas Herve]

When doing a block live migration with volumes attached, the libvirt drive-mirror operation tries to sync all the disks attached to the domain, even if they are external volumes. It should only do so for the ephemeral storage, so we need to be able to pass that information.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/125616

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: stable/icehouse
Review: https://review.openstack.org/126224

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean Dague (<email address hidden>) on branch: stable/icehouse
Review: https://review.openstack.org/126224
Reason: This review is > 4 weeks without comment and currently blocked by a core reviewer with a -2. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and contacting the reviewer with the -2 on this review to ensure you address their concerns.

[melanie witt (melwitt)]

Based on the comments in the proposed patch:

https://review.openstack.org/125616

the root cause of this issue requires enhancement in libvirt before anything can be done about it in nova. So, marking this as Opinion/Wishlist as an enhancement that can be addressed if libvirt is first enhanced.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean Dague (<email address hidden>) on branch: master
Review: https://review.openstack.org/125616
Reason: This review is > 4 weeks without comment and currently blocked by a core reviewer with a -2. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and contacting the reviewer with the -2 on this review to ensure you address their concerns.