[Openstack] [Nova][Glance] Nova imports flat images from base file despite ceph backend

melanie witt melwittt at gmail.com
Fri Oct 12 17:10:17 UTC 2018

On Tue, 09 Oct 2018 08:01:01 +0000, Eugen Block wrote:
> So it's still unclear why nova downloaded a raw glance image to the
> local filesystem during the previous attempt.
> I always knew that with Ceph as backend it's recommended to use raw
> images but I always assumed the "disk-format" was not more than a
> display option. Well, now I know that, but this still doesn't explain
> the downloaded base image.
> If anyone has an idea how to reproduce such behavior or an
> explanation, I'd love to hear it.

Right, in order to get the ceph CoW behavior, you must use RAW glance 
image format [1]. You also need to have created the image as 'raw' 
before you upload to glance (qemu-img info should show the file format 
as 'raw').

If you have done this, then you shouldn't see any image downloaded to 
the local filesystem. Is it possible that your image did not have file 
format 'raw' before you uploaded it to glance?


[1] http://docs.ceph.com/docs/master/rbd/rbd-openstack

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