Comment 4 for bug 1070272

Gabriel is correct, this is a work in progress... however, we have added something new to Cinder to make this a bit easier. You may however be referring to the read/write images addition to volumes that was added in Folsom (nova-vol and cinder).

You now have the ability to specify an image file when you create a volume. This will in effect copy the image to the volume and allow you to use it as a "bootable" volume. This feature is not in Horizon (it came in to Cinder pretty late in the release cycle), so it can only be done via the Cinder client/api.

After creating the volume, you can use boot from volume in Horizon as in the past (launch instance from the same image that you used in volume creation) and select 'boot from volume'. One note, currently this only works with raw images.

Let me know if this is what you're referring to, or if you had something else in mind.