Scaling down the cluster

Scaling down the cluster refers to the removal of cluster members.

These instructions show how to remove a node with the exception of the primary (bootstrap) node. For instructions on the latter, see page Removing the primary node. Note that, in terms of removing nodes, the primary node is always the last to be removed.

Remove the node

On the primary node:

sunbeam cluster remove --name <node FQDN>

Note: A current software issue (fixed in the edge risk level) causes the cluster remove command to fail with a message like:

ERROR removing machine failed: machine 1 has unit "sunbeam-machine/1" assigned.

To work around this manually remove the unit in the error message by issuing:

juju remove-unit sunbeam-machine/1

The cluster remove command can then be reissued.

Repeat the workaround as needed.

Remove components from the node

Software components now need to removed from the target node. Perform all the below steps on the target node.

Remove the Juju agent:

sudo /sbin/remove-juju-services

Remove the juju snap:

sudo snap remove --purge juju

Remove Juju configuration:

rm -rf ~/.local/share/juju

Remove the openstack-hypervisor and openstack snaps:

sudo snap remove --purge openstack-hypervisor
sudo snap remove --purge openstack

Remove the microk8s snap:

sudo microk8s leave
sudo snap remove --purge microk8s

The above steps can take a few minutes to complete.

Remove the disk(s) used by microceph on this node:

sudo microceph disk list
sudo microceph disk remove <OSD on this node>

Remove the microceph snap:

sudo snap remove --purge microceph

If required clean the disk(s) identified in the earlier command:

sudo dd if=/dev/zero of=<DISK PATH> bs=4M count=10

Caution: The dd command will result in the permanent erasure of data. It is vital that you have specified the correct disk path to avoid unintended data loss.

Clear the remaining network configuration with a reboot:

sudo reboot

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