Comment 14 for bug 1751842

If customize-failure-domain is enabled, then the Juju deployment *must* have multiple availability zones available, either through the Juju Availability Zone configuration, or through juju configuration on the ceph-osd charms (where you would need three+ application deployments).

When the customize-failure-domain is enabled, Ceph is instructed to spread replicas in the default pools across rack/row, which is not possible if there is not enough zones configured, causing the health to never become healthy.