Open Stack

On 26/08/2019 08:55, Teckelmann, Ralf, NMU-OIP wrote:
> Hi Florian,
> 
> Thanks for moving our conversation to the mailing list.
> 
> From the discussion on the ceph-mailing list I take (as of today):
> 
> - Ephemeral boot, *without* RBD, with or without attached volumes:
> freeze/thaw if hw_qemu_guest_agent=yes, resulting in consistent snapshots.
> 
> - Ephemeral boot *from* RBD, also with or without attached volumes: no
> freeze/thaw, resulting in potentially inconsistent snapshots even with
> hw_qemu_guest_agent=yes.
> 
> - Boot-from-volume from RBD: freeze/thaw if hw_qemu_guest_agent=yes,
> resulting in consistent snapshots.
> 
> One may note that " hw_qemu_guest_agent=yes" stands for 
> - the metadata property set on an image and as well 
> - assumes one does install the qemu-guest agent in that image or on the instances spawned from that image.
> Besides that, Florian explains further down why os_require_quiesce=yes is very nice to have set as well.

Right, also note that due to the fact that RBD-backed ephemeral images
currently bypass quiescing altogether, os_require_quiesce is actually
silently ignored for VMs that are RBD-backed AND do not boot from volume.

A Nova bug about this is open, and a discussion on how to best fix it is
currently ongoing:

https://bugs.launchpad.net/nova/+bug/1841160

Cheers,
Florian