Open Stack

On 08/11/15 at 01:42pm, Brian Rosmaita wrote:
>On 8/7/15, 1:07 PM, "Jay Pipes" <jaypipes at gmail.com> wrote:
>
>>So, here's the crux of the issue. Nova and Cinder **do not want to speak
>>the Glance REST API** to either upload or download image bits from
>>storage. Streaming image bits through the Glance API endpoint is a
>>needless and inefficient step, and Nova and Cinder would like to
>>communicate directly with the backend storage systems.
>
>Exactly why do you want to communicate directly with the backend storage
>systems?  Streaming image bits through Glance appears to be "needless and
>inefficient", but if an end-user is booting 1K instances from some custom
>image, Glance's image cache makes an enormous difference in delivery time.

Glance's image cache makes a big difference if the backend store has 
higher latency or less bandwidth than the Glance nodes themselves, but 
that will not always be the case.  And, AFAIK, it only allows for HTTP 
transfers of images and there are setups that would benefit from being 
able to grab the image via a different protocol.


>
>So I'm curious about what exactly the use cases for direct backend storage
>communication are, and why Glance can't meet them.
>
>cheers,
>brian
>
>
>
>
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