You already deployed successfully Joid and want to scale up ? this is how to add a compute node:

• Add a new compute node unit:

juju add-unit nova-compute 

• Check the new compute is ready

juju status --format=tabular | grep nova-compute

• Get the ID of your last added compute and add Ceph to this node:

ID=$(juju status --format=tabular | tail -n2 |head -n1 | cut -d\  -f1)
juju add-unit ceph-osd --to $ID

• Check ceph is ready

juju status --format=tabular | grep ceph-osd

juju set ceph-radosgw ceph-osd-replication-count=2