Instance snapshot is created with wrong image format

[Ankit Agrawal]

When you boot an instance with image of RAW image format then after taking instance snapshot it creates a snapshot with image format QCOW2.

Steps to reproduce using Horizon:

1. Go to Project --> Compute --> Images and click on 'Create Image'.
2. Create an image with 'Raw' format.
3. Go to Project --> Compute --> Instances and click on 'Launch Instance'.
4. Boot an instance by selecting the 'Boot from image' as source and newly created raw image from the Image Name drop-down.
5. Click on 'Create Snapshot' to create a snapshot of this instance.
6. You will be redirected to image list page where you will see the format of snapshot as 'QCOW2'.

Ideally the snapshot format should be same as its source image.

[Thang Pham (thang-pham)]

I do not believe this is a bug. You can configure which format your snapshot image is in nova.conf. Could you check what snapshot_image_format is in your nova.conf?

Snapshot image format (valid options are : raw, qcow2, vmdk, vdi). Defaults to same as source image

[Ankit Agrawal (ankitagrawal)]

Hi Thang, thanks to look into this issue. I rechecked my nova.conf where I don't have defined snapshot_image_format. It is not creating snapshot with source image format as documented in 'http://docs.openstack.org/trunk/config-reference/content/list-of-compute-config-options.html'.

[Thang Pham (thang-pham)]

This also depends on which cinder backend you are using. Which one are you using? For file based volumes, e.g. glusterfs, snapshots are in qcow2 format because that is the only way to do so.