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[Vishvananda Ishaya <vishvananda@xxxxxxxxx>]

?

Did you mistype your comment or misread mine?  Raw does NOT work for snapshots. snapshots only work for qcow2. Implementing snapshotting with raw would be possible. Logic just needs to be added to skip the internal snapshot step and just use the entire file when uploading to glance.  This would be pretty darn slow for large images though.

If you are asking about differencing images in glance that is a different question and one that we haven't addressed. It has a lot of implications and needs changes in both nova and glance to be useful. Logic needs to be added around dependency chains and coalescing. Plus it has implications when trying to migrate and resize instances, so there is a lot to consider.

As caitlin mentioned, something will be implemented in the volume service anyway, so it might be better to wait and see what happens there.

Vish

On Apr 24, 2012, at 4:30 PM, Joshua Harlow wrote:

> What changes would be needed to make qcow2 files work as snapshots?
> Some type of image “dependency” management in glance (and failure cases) and the corresponding “dependency” fetching in nova (and failure cases)?
> Might be something pretty useful to have, instead of forcing raw for snapshots?
> 
> On 4/24/12 3:51 PM, "Vishvananda Ishaya" <vishvananda@xxxxxxxxx> wrote:
> 
> On Apr 17, 2012, at 2:04 AM, William Herry wrote:
> 
> > so, what changes should I make if I want use raw in openstack, I didn't find some configure option in nova.conf.sample
> >
> > I also try to modify the source code in nova/virt/libvirt/utils.py, and didn't succeed
> >
> > I noticed that the type of snapshot is same as the instance's image by default, does this right, and what about the type of model image that uploaded to glance, does it affect the disk type I use?
> >
> > Thanks
> 
> snapshots will not work with raw images.  To make openstack use raw images, you simply have to set:
> 
> use_cow_images=false
> 
> you can upload to glance in qcow or raw, it will be decoded to raw when the image is downloaded to the compute host.
> 
> Vish
> 
> 
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