You can just flatten the image to make it independent from the parent 
image. After flattening (rbd flatten) you could sparsify it to get 
some storage capacity back.

Zitat von Satish Patel <satish.txt@gmail.com>:

> Folks,
>
> I have two openstack clouds and both have their own Ceph backend storage.I
> am trying to migrate instances from openstack A to openstack B.
>
> 1. Take a snapshot from A
> 2.  Export snapshot and import to B
> 3. Create instance on B
> 4. Delete snapshot - (I am getting error because its in-use)
>
> Because it has a parent reference to that volume. How do I remove the
> reference so it will let me delete a snapshot. Reason I am asking is
> because I have so many VMs to migrate and don't want glance to have 100s of
> entities in those snapshots.
>
> What is the alternative here? I can try qcow2 if that is the final solution
> to make it clean.
>
> # rbd -p volumes info volume-f2b2aec2-cc57-49e5-aca1-54b5a7ee9f3a
> rbd image 'volume-f2b2aec2-cc57-49e5-aca1-54b5a7ee9f3a':
>       size 40 GiB in 5120 objects
>       order 23 (8 MiB objects)
>       snapshot_count: 0
>       id: 5473c827864fed
>       block_name_prefix: rbd_data.5473c827864fed
>       format: 2
>       features: layering, exclusive-lock, object-map, fast-diff, deep-flatten
>       op_features:
>       flags:
>       create_timestamp: Fri Jan 19 19:03:25 2024
>       access_timestamp: Wed Jan 24 15:51:04 2024
>       modify_timestamp: Wed Jan 24 15:52:40 2024
>       parent: images/3708f961-fb74-49f1-ab9b-40cf7954abed@snap
>       overlap: 40 GiB