Open Stack

On 9/13/2017 10:31 AM, Morgenstern, Chad wrote:
> I have been studying how to perform failover operations with Cinder --failover.  Nova is not aware of the failover event. Being able to refresh the connection state especially for Nova would come in very handy, especially in admin level dr scenarios.
> 
> I'm attaching the blog I wrote on the subject:
> http://netapp.io/2017/08/09/cinder-cheesecake-things-to-consider/

I'm not aware of the host failover feature in Cinder, but you're correct 
that there is no event listener on the nova side for this happening.

You could build something like this into the os-server-external-events 
API in Nova:

https://developer.openstack.org/api-ref/compute/#create-external-events-os-server-external-events

That is used today for Cinder to trigger a swap volume or volume extend 
operation in Nova. It would require a microversion and spec in nova, but 
it doesn't seem that hard to do, depending on what you need to do on the 
nova side. With the new 3.27 Cinder attachments APIs, it seems it could 
just be an attachment delete/create operation, but would we also need to 
disconnect old/connect new connections in os-brick?

-- 

Thanks,

Matt