[openstack-dev] [nova][cinder] About rebuilding volume-backed instances.

Clint Byrum clint at fewbar.com
Mon Nov 9 07:28:30 UTC 2015


Excerpts from Zhenyu Zheng's message of 2015-11-08 23:04:59 -0800:
> Hi All,
> 
> Currently, we have strong demands about "rebuilding"(or actions like
> rebuilding) volume-backed instances. As in production deployment, volume
> backed instance is widely used. Users have the demands of performing the
> rebuild(recovery) action for root device while maintain instance UUID sorts
> of information, many users also wants to keep the volume uuid unchanged.
> 
> Nova side doesn't support using Rebuild API directly for volume backed
> instances (the volume will not change). And Nova side also doesn't support
> detaching root device, that means we cannot performing volume
> backup/restore from cinder side, because those actions needs the volume in
> "available" status.
> 
> Now there are couple of patches proposed in nova trying to fix this problem:
> [1] https://review.openstack.org/#/c/201458/
> [2] https://review.openstack.org/#/c/221732/
> [3] https://review.openstack.org/#/c/223887/
> 
> [1] and [2] are trying to expose the API of detaching root devices, [3] is
> trying to fix it in the current Rebuild API. But yet none of them got much
> attention.
> 
> As we now have strong demand on performing the "rebuilding" action for
> volume-backed instances, and yet there is not any clear information about
>  it. I wonder is there any plans of how to support it in Nova and Cinder?
> 

This seems entirely misguided by the users.

Why not just boot a new instance on a new volume with the same image?
Names can be the same.. UUID's should never be anything except a physical
handle.



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