MySQL InnoDB Cluster Restore/Create Issue : - Dba.createCluster: Group Replication failed to start: MySQL Error 3094 (HY000)

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MySQL InnoDB Cluster Restore Issue : - Dba.createCluster: Group Replication failed to start: MySQL Error 3094 (HY000)


Recently ,We have been restoring and recreating MySQL InnoDB Cluster and faced below issue after firing :

MySQL mysqlhost01:3306 ssl JS > var cluster = dba.createCluster('testdbCluster')
..
.....
...
Creating InnoDB cluster 'testdbCluster' on 'mysqlhost01:3306'...
Adding Seed Instance...
ERROR: Unable to start Group Replication for instance 'mysqlhost01:3306'. Please check the MySQL server error log for more information.
Dba.createCluster: Group Replication failed to start: MySQL Error 3094 (HY000): mysqlhost01:3306: The START GROUP_REPLICATION command failed as the applier module failed to start. (RuntimeError)
MySQL mysqlhost01:3306 ssl JS >

Below is full command output with error message:

Below are the message in MySQL error log:


This issue is Caused by the old(original server) relay log information exiting in metadata tables. Because we are restoring old MySQL InnoDB Cluster on new hosts(mysqlhost01,.mysqlhost02,mysqlhost03).


As we are restoring Old MySQL InnoDB Cluster on the new host ,We can truncate  mysql.slave_relay_log_info table to resolve issue.

mysql>  set sql_log_bin=off;
Query OK, 0 rows affected (0.00 sec)
mysql> SET GLOBAL super_read_only =0;
Query OK, 0 rows affected (0.00 sec)
mysql>  truncate mysql.slave_relay_log_info;
mysql> commit;
systemctl restart mysql
select @@super_read_only();


NOTE: Be care full do not run this when restoring backup on the same cluster servers.

Post following the resolution steps, We was able to create MySQL InnoDB Cluster.



Ref : MySQLInnodb Cluster Node Failed To Start With Error: "[ERROR] Slave SQL for channel 'group_replication_applier': Slave failed to initialize relay log info structure from the repository, Error_code: 1872" (Doc ID 2386403.1)

you can learn more about MySQL database using below books:
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You can also , Visit our Blogs for related topic on MySQL InnoDB Cluster:
1)MySQL InnoDB Cluster node Addition Issue: - Cluster.addInstance: : MySQL server has gone away (RuntimeError)
2)Install & Configure MySQL Router -  MySQL InnoDB Cluster
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