I have a production MariaDB Galera 5 node cluster that has been running for about 8 months at our factory. One node had a powerfail / un-graceful shutdown (Ubuntu 16.04) and since then if that node is up, it causes the entire cluster to permanently respond with "wsrep has not yet prepared node for application use". If I shut down that node and restart the cluster, all is fine. My suspicion is the ungraceful shutdown caused some file system issues that cause the entire cluster to be unusable. Just curious if anyone else has seen this.