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On 3/15/2018 5:29 PM, Dan Smith wrote:
> Yep, for sure. I think if there are snapshots, we have to refuse to do
> te thing. My comment was about the "does nova have authority to destroy
> the root volume during a rebuild" and I think it does, if
> delete_on_termination=True, and if there are no snapshots.

Agree with this.

Things do get a bit weird with delete_on_termination and if nova 'owns' 
the volume. delete_on_termination is False by default, even if you're 
doing boot from volume with source_type of 'image' or 'snapshot' where 
nova creates the volume for you.

If a user really cared about preserving the volume, they'd probably 
pre-create it (with their favorite volume type since you can't tell nova 
the volume type to use) and pass it to nova with 
delete_on_termination=False explicitly.

Given the defaults, I'm not sure how many people are going to specify 
delete_on_termination=True, thinking about the implications, which then 
means they can't rebuild their volume-backed instance later because nova 
can't / won't delete the volume.

If we can solve this without deleting the volume at all and just 
re-image it, then it's a non-issue.

-- 

Thanks,

Matt