[openstack-dev] [nova][libvirt] Block migrations and Cinder volumes
chris.friesen at windriver.com
Tue Mar 17 21:20:29 UTC 2015
On 03/17/2015 02:33 PM, Joe Gordon wrote:
> Digging up this old thread because I am working on getting multi node live
> migration testing working (https://review.openstack.org/#/c/165182/), and just
> ran into this issue (bug 1398999).
> And I am not sure I agree with this statement. I think there is a valid case for
> doing block migrate with a cinder volume attached to an instance:
> * Cloud isn't using a shared filesystem for ephemeral storage
> * Instance is booted from an image, and a volume is attached afterwards. An
> admin wants to take the box the instance is running on offline for maintanince
> with a minimal impact to the instances running on it.
> What is the recommended solution for that use case? If the admin disconnects and
> reconnects the volume themselves is there a risk of impacting whats running on
> the instance? etc.
Interesting bug. I think I agree with you that there isn't a good solution
currently for instances that have a mix of shared and not-shared storage.
I'm curious what Daniel meant by saying that marking the disk shareable is not
as reliable as we would want.
I think there is definitely a risk if the admin disconnects the volume--whether
or not that causes problems depends on whether the application can handle that
I suspect the "proper" cloud-aware strategy would be to just kill it and have
another instance take over. But that's not very helpful for
Also, since you've been playing in this area...do you know if we currently
properly support all variations on live/cold migration, resize, evacuate, etc.
for the boot-from-volume case?
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