--- other: - | `Numbered request groups`_ can be defined in the flavor extra_spec but they can come from other sources as well (e.g. neutron ports). If there is more than one numbered request group in the allocation candidate query and the flavor does not specify any group policy then the query will fail in placement as group_policy is mandatory in this case. Nova previously printed a warning to the scheduler logs but let the request fail. However the creator of the flavor cannot know if the flavor later on will be used in a boot request that has other numbered request groups. So nova will start defaulting the group_policy to 'none' which means that the resource providers fulfilling the numbered request groups can overlap. Nova will only default the group_policy if it is not provided in the flavor extra_spec, and there is more than one numbered request group present in the final request, and the flavor only provided one or zero of such groups. .. _`Numbered request groups`: https://docs.openstack.org/nova/latest/user/flavors.html#extra-specs-numbered-resource-groupings