After multiple networking connectivity issues between MySQL InnoDB Cluster nodes, the cluster may break and the MySQL Router begins to log the following messages:
2022-10-11 15:20:48 metadata_cache ERROR [7f2d619fe640] Unable to fetch live group_replication member data from any server in cluster 'mycluster1' 2022-10-11 15:20:49 metadata_cache WARNING [7f2d619fe640] Member db-cluster-2:3306 (05b6c7c7-f285-11ec-adfc-00163e0b38ff) defined in metadata not found in actual Group Replication 2022-10-11 15:20:49 metadata_cache WARNING [7f2d619fe640] db-cluster-1:3306 is not part of quorum for cluster 'mycluster1' 2022-10-11 15:20:49 metadata_cache WARNING [7f2d619fe640] Member db-cluster-1:3306 (8bf2c25f-90ae-11ec-93d1-00163e20a401) defined in metadata not found in actual Group Replication 2022-10-11 15:20:49 metadata_cache WARNING [7f2d619fe640] db-cluster-3:3306 is not part of quorum for cluster 'mycluster1' 2022-10-11 15:20:49 metadata_cache WARNING [7f2d619fe640] Member db-cluster-3:3306 (99856952-90ae-11ec-9a5f-fafd8f1acc17) defined in metadata not found in actual Group Replication 2022-10-11 15:20:49 metadata_cache WARNING [7f2d619fe640] db-cluster-2:3306 is not part of quorum for cluster 'mycluster1'
And in MySQL nodes there are also the errors of unable to connect to 33061:
2022-10-11T15:16:25.728393Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] Error on opening a connection to peer node db-cluster-1:33061 when joining a group. My local port is: 33061.' 2022-10-11T15:16:25.728714Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] Error on opening a connection to peer node db-cluster-3:33061 when joining a group. My local port is: 33061.' 2022-10-11T15:16:25.729195Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] Error on opening a connection to peer node db-cluster-1:33061 when joining a group. My local port is: 33061.' 2022-10-11T15:16:25.729569Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] Error on opening a connection to peer node db-cluster-3:33061 when joining a group. My local port is: 33061.' 2022-10-11T15:16:25.730154Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] Error on opening a connection to peer node db-cluster-1:33061 when joining a group. My local port is: 33061.' 2022-10-11T15:16:25.730474Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] Error on opening a connection to peer node db-cluster-3:33061 when joining a group. My local port is: 33061.' 2022-10-11T15:16:25.730485Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] Error connecting to all peers. Member join failed. Local port: 33061' 2022-10-11T15:16:25.782015Z 0 [ERROR] [MY-011735] [Repl] Plugin group_replication reported: '[GCS] The member was unable to join the group. Local port: 33061'
When a MySQL Cluster node node cannot connect to the 33061 (or 3306X), it may be a signal for a firewall issue or the group replication has not started on this node, which is the case here!
The group replication is not working and the cluster must be recovered. All nodes wait to join an exiting cluster, which is not available. It has not stared yet and it would not start alone even the administrator may restart all the nodes.
Keep on reading!