You're probably going to want to look at the proposals for volume
consistency groups in cinder - backing up/snapshotting volumes
independently is likely to cause issues with some applications, since
different VMs will be in slightly different states, so you can get
lost or duplicated work/records/etc

On 15 April 2014 12:16, Thomas Herve <[email protected]> wrote:
> Hi all,
>
> I started working on the stack snapshot blueprint [1] and wrote a first 
> series of patches [2] to get a feeling of what's possible. I have a couple of 
> related design questions though:
>
>  * Is a stack snapshot independent of the stack? That's the way I chose for 
> my patches, you start with a stack, but then you can show and delete 
> snapshots independently. The main impact will be how restoration works: is 
> restoration an update action on a stack towards a specific state, or a 
> creation action with backup data?
>
>  * Consequently, should be use volume backups (which survive deleting of the 
> original volumes) or volume snapshots (which don't). If the snapshot is 
> dependent of the stack, then we can use the more efficient snapshot 
> operation. But backup is also an interesting use-case, so should it be 
> another action completely?
>
>
> [1] https://blueprints.launchpad.net/heat/+spec/stack-snapshot
>
> [2] 
> https://review.openstack.org/#/q/status:open+project:openstack/heat+branch:master+topic:bp/stack-snapshot,n,z
>
> Thanks,
>
> --
> Thomas
>
> _______________________________________________
> OpenStack-dev mailing list
> [email protected]
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev



-- 
--
Duncan Thomas

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