Comment 2 for bug 1611826

Nadezhda, snapshot delete operation works in async mode, it means we can't return appropriate error message once we call API. More user-friendly messages will be implemented in scope of [1] spec in Newton. It means we can't backport it to MOS 9 or MOS 8.

From the Cinder's perspective, it's incorrect behavior. If you create volume from snapshot, you should be able to delete a snapshot. It's an issue in RBD driver and should be fixed. We could backport this fix to MOS 8 and MOS 9 once fix will be available if needed.

https://github.com/openstack/cinder-specs/blob/master/specs/newton/summarymessage.rst