I have 3 node cluster ( 2 data node and one arbitrator ). The percona cluster version is Percona-XtraDB-Cluster-57-5.7.36-31.55.1 on these nodes. I am getting warnings in my error logs which means that I need to run mysql_upgrade. As it is active cluster so I was not sure how I should plan it. I tried to google but could not get clear answer. Please check the following steps that I was thinking and correct me if I am missing anything.
1- Remove the 2 nodes from the cluster so that there is only one node left.
2- Run mysql_upgrade on the running one node ( do we need to do restart the node once we do it ? So we will be bootstraping the only node in cluster )
3- Start the other nodes in the cluster. ( The changes will be replicated automatically on the other nodes, Please correct me if it is not the case ).