On 11/12/2013 8:09 AM, John Griffith wrote:
On Tue, Nov 12, 2013 at 8:46 AM, Solly Ross <sr...@redhat.com> wrote:
I'd like to get some sort of consensus on this before I start working on it.  
Now that people are back from Summit, what would you propose?

Best Regards,
Solly Ross

----- Original Message -----
From: "Solly Ross" <sr...@redhat.com>
To: "OpenStack Development Mailing List (not for usage questions)" 
<openstack-dev@lists.openstack.org>
Sent: Tuesday, November 5, 2013 10:40:48 AM
Subject: Re: [openstack-dev] Improvement of Cinder API wrt 
https://bugs.launchpad.net/nova/+bug/1213953

Also, that's still an overly complicated process for one or two VMs.  The idea behind 
the Nova command was to minimize the steps in the image->volume->VM process for 
a single VM.


Complexity is not an issue. Bandwidth and latency are issues.

Any solution that achieves the user objectives can be managed by a taskflow. It will be simple for the user to apply. The amount of code
involved is relatively low on the factors to compare. Taking extra time
and consuming extra bandwidth that were not required are serious issues.

My assumption is that the cinder backend will be able to employ copy-on-write when cloning volumes to at least make a thinly provisioned version available almost instantly (even if the full space is allocated and then copied asynchronously. Permanently thin clones just require that the relationship be tracked. Currently that is up to the volume driver, but we could always make these relationships legitimate by recognizing them in Cinder proper).

The goal here is not to require new behaviors of backends, but to enable
solutions that already exist to be deployed to the benefit of end users.
Requiring synchronoous multi-GB copies (locally or even worse over the
network) is not a minor price that we should expect customers to endure
for the sake of software uniformity.



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