Exporting volumes from Cinder and re-creating COW layers
Today I wandered into a bit of a rat hole discovering how to export data from OpenStack Cinder volumes when you don't have admin permissions, and I thought it was worth documenting here so I remember it for next time. Let's assume that you have a Cinder volume named "child1", which is a 64gb volume originally cloned from "parent1". parent1 is a 7.9gb VMDK, but the only way I can find to extract child1 is to convert it to a glance image and then download the entire volume as a raw. Something like this: $ cinder upload-to-image $child1 "extract:$child1" Where $child1 is the UUID of the Cinder volume. You then need to find the UUID of the image in Glance, which the Cinder upload-to-image command will have told you, but you can also find by searching Glance for your image named "extract:$child1": $ glance image-list | grep "extract:$cinder_uuid" You now need to watch that Glance image until the status of the image is "active". It will go through a series of steps with names like "queued", and "uploading" first. Now you can download the image from Glance: $ glance image-download --file images/$child1.raw --progress $glance_uuid And then delete the intermediate glance…