[openstack-dev] [nova] Should we make rebuild + new image on a volume-backed instance fail fast?

Matt Riedemann mriedemos at gmail.com
Fri Oct 6 22:30:11 UTC 2017

On 10/6/2017 1:10 PM, Mathieu Gagné wrote:
> I don't think there ever was a technical limitation to add support for it.

See the review comments with the -1 votes on the patches I linked 

There are valid technical reasons for the -1s on those, including on 
this one from Paul Murray - who spent more time than probably anyone 
trying to get nova to support detach/attach root volumes:


Quoth Dr Murray:

"There is actually a lot more to this than detaching and attaching the 
volume - doing that alone is unsafe because the rest of the code assumes 
there is a root device. So if nova tries to do anything with the 
instance when the volume is detached it will probably fail and to error 
(e.g. delete, migrate, resize, start). All of these cases have to be 
fixed as well as the volume. We also need to make sure that only another 
volume can be attached or handle the case for swapping in any kind of 
storage device (an image on ephemeral disk for example)."

I'm fine with people wanting to resume his old spec and code if someone 
wants to own that, but I can't say it's going to be a review priority.




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