Comment 3 for bug 1876104

To try and cover the points raised so far...

Juju is conservative when there's the possibility of deleting people's data, that's why destroying a model with storage requires an explicit decision whether to destroy the volumes or just release them and allow them to be reattached later or otherwise accessed by the user to get any data.

Juju also always attempts to cleanly destroy a model - this means that units have to fully run any relation departed/broken hooks etc, and the storage provioner worker has to be able to cleanly detach any volumes and report back that it has done so. If any of this fails, the model will not get cleaned up.

To allow for cases where a model cannot be destroyed cleanly (eg someone removed an openstack instance or cinder volume outside of juju), the --force option can be used. This will ignore cloud errors and continue with the model destruction. In juju 2.8, some fixes were added to address issues with --force and storage. Previously, --force didn't always work well with storage.

There's ongoing work to improve feedback from model destroy operations, but the current expectation is that --force at least should do what it says on the tin.

I'll mark as incomplete pending any further feedback that there's still an issue with Juju 2.8.0