Apology for my poor English!!! we have 3 Group Replication Node :oms-mysql-01(read/write node ) กข oms-mysql-02 (backup node ) and oms-mysql-03 (write node ). Sometimes, GR will be halt,like this: oms-mysql-01: 2018-06-28T16:12:51.856239+08:00 468191 [Note] Aborted connection 468191 to db: 'kingkoo_oms' user: 'kingkoo' host: '10.10.19.32' (Got an error reading communication packets) 2018-06-28T16:12:51.856239+08:00 466091 [Note] Aborted connection 466091 to db: 'kingkoo_oms' user: 'kingkoo' host: '10.10.19.32' (Got an error reading communication packets) 2018-06-28T16:15:37.287348+08:00 0 [Warning] Plugin group_replication reported: 'Member with address oms-mysql-03l:6603 has become unreachable.' 2018-06-28T16:15:37.498239+08:00 0 [Note] Plugin group_replication reported: '[GCS] Removing members that have failed while processing new view.' 2018-06-28T16:15:37.502426+08:00 0 [Note] Plugin group_replication reported: 'getstart group_id 98bfbda8' 2018-06-28T16:15:38.290143+08:00 0 [Warning] Plugin group_replication reported: 'Members removed from the group: oms-mysql-03l:6603' 2018-06-28T16:15:38.290248+08:00 0 [Note] Plugin group_replication reported: 'Group membership changed to oms-mysql-02l:6603, oms-mysql-01l:6603 on view 15297674028351813:6.' 2018-06-28T16:17:19.670446+08:00 468238 [Note] Aborted connection 468238 to db: 'kingkoo_oms' user: 'kingkoo' host: '10.10.19.24' (Got an error reading communication packets) oms-mysql-03 2018-06-28T16:12:19.697546+08:00 223105 [Note] Aborted connection 223105 to db: 'interface_bus' user: 'kingkoo' host: '10.10.19.24' (Got an error reading communication packets) 2018-06-28T16:12:19.697587+08:00 223138 [Note] Aborted connection 223138 to db: 'interface_bus' user: 'kingkoo' host: '10.10.19.24' (Got an error reading communication packets) 2018-06-28T16:12:19.697542+08:00 223136 [Note] Aborted connection 223136 to db: 'kingkoo_oms' user: 'kingkoo' host: '10.10.19.24' (Got an error reading communication packets) 2018-06-28T16:15:39.954935+08:00 0 [Note] Plugin group_replication reported: 'getstart group_id 98bfbda8' 2018-06-28T16:15:40.019136+08:00 0 [Note] InnoDB: page_cleaner: 1000ms intended loop took 13198ms. The settings might not be optimal. (flushed=8 and evicted=0, during the time.) 2018-06-28T16:15:41.293922+08:00 0 [ERROR] Plugin group_replication reported: 'Member was expelled from the group due to network failures, changing member status to ERROR.' 2018-06-28T16:15:41.294325+08:00 0 [ERROR] Plugin group_replication reported: 'Message received while the plugin is not ready, message discarded' 2018-06-28T16:15:42.956119+08:00 0 [Note] Plugin group_replication reported: 'state 4410 action xa_terminate' 2018-06-28T16:15:42.956517+08:00 0 [Note] Plugin group_replication reported: 'new state x_start' 2018-06-28T16:15:42.956529+08:00 0 [Note] Plugin group_replication reported: 'state 4337 action xa_exit' 2018-06-28T16:15:42.956598+08:00 0 [Note] Plugin group_replication reported: 'Exiting xcom thread' 2018-06-28T16:15:42.956619+08:00 0 [Note] Plugin group_replication reported: 'new state x_start' 2018-06-28T16:19:25.928992+08:00 223142 [Note] Aborted connection 223142 to db: 'interface_bus' user: 'kingkoo' host: '10.10.19.23' (Got an error reading communication packets) 2018-06-28T16:20:35.596225+08:00 0 [Note] InnoDB: page_cleaner: 1000ms intended loop took 11100ms. The settings might not be optimal. (flushed=2000 and evicted=0, during the time.) 2018-06-28T16:22:19.728665+08:00 223145 [Note] Aborted connection 223145 to db: 'kingkoo_oms' user: 'kingkoo' host: '10.10.19.24' (Got an error reading communication packets) 2018-06-28T16:22:19.728708+08:00 223089 [Note] Aborted connection 223089 to db: 'kingkoo_oms' user: 'kingkoo' host: '10.10.19.24' (Got an error reading communication packets) 2018-06-28T16:24:14.527240+08:00 223155 [Note] Plugin group_replication reported: 'Plugin 'group_replication' is stopping.' 2018-06-28T16:24:14.527320+08:00 223155 [Note] Plugin group_replication reported: 'Going to wait for view modification' 2018-06-28T16:24:14.527413+08:00 0 [Warning] Plugin group_replication reported: 'read failed' 2018-06-28T16:24:14.527728+08:00 0 [Note] Plugin group_replication reported: 'Group membership changed: This member has left the group.' 2018-06-28T16:24:19.527976+08:00 223155 [Note] Plugin group_replication reported: 'auto_increment_increment is reset to 1' 2018-06-28T16:24:19.528025+08:00 223155 [Note] Plugin group_replication reported: 'auto_increment_offset is reset to 1' 2018-06-28T16:24:19.528265+08:00 134911 [Note] Error reading relay log event for channel 'group_replication_applier': slave SQL thread was killed 2018-06-28T16:24:19.535372+08:00 134908 [Note] Plugin group_replication reported: 'The group replication applier thread was killed' 2018-06-28T16:24:19.537454+08:00 223155 [Note] Plugin group_replication reported: 'Plugin 'group_replication' has been stopped.' 2018-06-28T16:24:40.876199+08:00 223155 [Note] Plugin group_replication reported: 'Group communication SSL configuration: group_replication_ssl_mode: "DISABLED"' 2018-06-28T16:24:40.876314+08:00 223155 [Note] Plugin group_replication reported: '[GCS] Added automatically IP ranges 10.10.19.27/24,127.0.0.1/8 to the whitelist' 2018-06-28T16:24:40.876437+08:00 223155 [Note] Plugin group_replication reported: '[GCS] SSL was not enabled' but , there is a ping script task on oms-mysql-01, here is the log (10.10.19.27 is oms-mysql-03): ip=10.10.19.27 rtt=1.1 ms seq=190742 20180628161517 ip=10.10.19.27 rtt=0.3 ms seq=190743 20180628161518 ip=10.10.19.27 rtt=0.3 ms seq=190744 20180628161519 ip=10.10.19.27 rtt=0.3 ms seq=190745 20180628161520 ip=10.10.19.27 rtt=0.3 ms seq=190746 20180628161521 ip=10.10.19.27 rtt=0.5 ms seq=190747 20180628161522 ip=10.10.19.27 rtt=0.3 ms seq=190748 20180628161523 ip=10.10.19.27 rtt=0.3 ms seq=190749 20180628161524 ip=10.10.19.27 rtt=0.3 ms seq=190750 20180628161525 ip=10.10.19.27 rtt=0.3 ms seq=190751 20180628161526 ip=10.10.19.27 rtt=0.3 ms seq=190752 20180628161527 ip=10.10.19.27 rtt=0.3 ms seq=190753 20180628161529 ip=10.10.19.27 rtt=0.3 ms seq=190754 20180628161530 ip=10.10.19.27 rtt=1.5 ms seq=190755 20180628161531 ip=10.10.19.27 rtt=0.4 ms seq=190756 20180628161532 ip=10.10.19.27 rtt=0.3 ms seq=190757 20180628161533 ip=10.10.19.27 rtt=0.3 ms seq=190758 20180628161534 ip=10.10.19.27 rtt=0.3 ms seq=190759 20180628161535 ip=10.10.19.27 rtt=0.3 ms seq=190760 20180628161536 ip=10.10.19.27 rtt=0.3 ms seq=190761 20180628161537 ip=10.10.19.27 rtt=1.5 ms seq=190762 20180628161538 ip=10.10.19.27 rtt=7.4 ms seq=190763 20180628161539 ip=10.10.19.27 rtt=0.9 ms seq=190764 20180628161540 ip=10.10.19.27 rtt=0.3 ms seq=190765 20180628161541 ip=10.10.19.27 rtt=0.4 ms seq=190766 20180628161542 ip=10.10.19.27 rtt=0.4 ms seq=190767 20180628161544 ip=10.10.19.27 rtt=0.3 ms seq=190768 20180628161545 ip=10.10.19.27 rtt=0.3 ms seq=190769 20180628161546 ip=10.10.19.27 rtt=0.4 ms seq=190770 20180628161547 ip=10.10.19.27 rtt=0.5 ms seq=190771 20180628161548 ip=10.10.19.27 rtt=0.4 ms seq=190772 20180628161549 ip=10.10.19.27 rtt=0.4 ms seq=190773 20180628161550 ip=10.10.19.27 rtt=0.4 ms seq=190774 20180628161551 so ,why does the oms-mysql-03 been unreachable ? (Member with address oms-mysql-03l:6603 has become unreachable) thanks!!! group_replication_allow_local_disjoint_gtids_join OFF group_replication_allow_local_lower_version_join OFF group_replication_auto_increment_increment 7 group_replication_bootstrap_group OFF group_replication_components_stop_timeout 31536000 group_replication_compression_threshold 1000000 group_replication_enforce_update_everywhere_checks OFF group_replication_flow_control_applier_threshold 5000 group_replication_flow_control_certifier_threshold 5000 group_replication_flow_control_mode QUOTA group_replication_force_members group_replication_group_name 7090b84d-2f6d-4cd4-896e-17ed82c64b8c group_replication_group_seeds 10.10.19.25:26603,10.10.19.26:26603,10.10.19.27:26603 group_replication_gtid_assignment_block_size 1000000 group_replication_ip_whitelist AUTOMATIC group_replication_local_address 10.10.19.27:26603 group_replication_member_weight 50 group_replication_poll_spin_loops 0 group_replication_recovery_complete_at TRANSACTIONS_APPLIED group_replication_recovery_reconnect_interval 60 group_replication_recovery_retry_count 10 group_replication_recovery_ssl_ca group_replication_recovery_ssl_capath group_replication_recovery_ssl_cert group_replication_recovery_ssl_cipher group_replication_recovery_ssl_crl group_replication_recovery_ssl_crlpath group_replication_recovery_ssl_key group_replication_recovery_ssl_verify_server_cert OFF group_replication_recovery_use_ssl OFF group_replication_single_primary_mode ON group_replication_ssl_mode DISABLED group_replication_start_on_boot OFF group_replication_transaction_size_limit 0 group_replication_unreachable_majority_timeout 120