>
> Although it wouldn't help making a consistent snapshot of an instance
> with multiple disks, for a single disk it shouldn't matter if the
> guest is quiesced as long as the backend can make an instantaneous
> snapshot. I'm pretty sure many (most?) backends would support that;
> certainly plain old LVM does. Does cinder use this functionality where
> it's available, and would that solve the problem you're trying to
> address?
>
> Matt
>

That is a good point. If you snap all of the volumes used, it may not be
quiesced and have all IO flushed, but it would at least be a crash consistent
set of data.

All of the volumes used by a VM would need to be added to a group:

https://docs.openstack.org/cinder/latest/admin/blockstorage-groups.html

You would then be able to create a group snapshot to have all volumes snapped
together.