Sometimes when adding a node to the cluster, it gets stuck in a JOINING state (UJ) and never completes the process to an Up-Normal (UN) state. The only solution is to remove the node. As long as the node did not join the cluster, meaning it never went into UN state, you can stop this node, clean its data, and try again.
Run the nodetool drain command (Scylla stops listening to its connections from the client and other nodes).
Stop the node
sudo systemctl stop scylla-server
sudo service scylla-server stop
docker exec -it some-scylla supervisorctl stop scylla
(without stopping some-scylla container)
Clean the data
sudo rm -rf /var/lib/scylla/data sudo find /var/lib/scylla/commitlog -type f -delete sudo find /var/lib/scylla/hints -type f -delete sudo find /var/lib/scylla/view_hints -type f -delete
Start the node
sudo systemctl start scylla-server
sudo service scylla-server start
docker exec -it some-scylla supervisorctl start scylla
(with some-scylla container already running)