Shutdown

systemctl stop mariadb                 # on all nodes - remember shutdown order!
systemctl disable mariadb.service      # optional on all nodes

Poweron

galera_new_cluster                     # on last stopped node
systemctl enable mariadb.service       # optional on all nodes
systemctl start mariadb                # on all other nodes after second node is synced

check cluster

SHOW STATUS LIKE 'wsrep_%';