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Thanks for the feedback!

I need to look closer to Cinder Agent specs.

Walter,
Hope, I could help you and Duncan with making this.

Regards,
Ivan Kolodyazhny

On Wed, Sep 17, 2014 at 2:32 AM, Mathieu Gagné <mgagne at iweb.com> wrote:

> On 2014-09-16 7:03 PM, Walter A. Boring IV wrote:
>
>  The upside to brick not making it in Nova is that it has given us some
>> time to rethink things a bit.  What I would actually
>> like to see happen now is to create a new cinder/storage agent instead
>> of just a brick library.   The agent would run on every cinder node,
>> nova node and potentially ironic nodes to do LUN discovery. Duncan and I
>> are looking into this for the Kilo release.
>>
>>
> Thanks for reviving this idea [1] [2] [3]. I wish to say that I like it
> because months ago, we found use cases for it and wished cinder-agent was a
> thing.
>
> One use case we have is the need to rescan an iSCSI target used by a Nova
> instance after an in-use volume has been extended in order to reflect its
> new size at the hypervisor level.
>
> During the implementation, we quickly saw the code duplication hell that
> exists between both Nova and Cinder, all implementing iSCSI management. Due
> to the amount of work required to introduce a cinder-agent and due to my
> inexperience with OpenStack back then, we went down an other path instead.
>
> We addressed our needs by introducing a Cinder->Nova interaction through
> custom code in Cinder and an API extension in Nova: Cinder triggers the
> rescan through the Nova API (instead of cinder-agent).
>
> With cinder-agent, Cinder would be able to remotely trigger a rescan of
> the iSCSI target without relying on a custom API extension in Nova. I feel
> this implementation would be much more resilient and reduce code
> duplication in the long term.
>
> I'm sure there is more use cases. This is mine.
>
> [1] https://blueprints.launchpad.net/cinder/+spec/cinder-agent
> [2] https://lists.launchpad.net/openstack/msg19825.html
> [3] https://etherpad.openstack.org/p/cinder-agent
>
> --
> Mathieu
>
>
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