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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?

I think this is something that should be addressed in the new block storage project, and only incidentally in glance.
Basically, glance can record the intent of X being based on snapshot Y, but building a volume X that is based on some
copy of snapshot Y is best left to the block layer.

Any solution expressed at the Glance layer is going to be biased towards doing the cloning too early.