Group Replication Security | s2 | 3306 | ONLINE | | s1 | 3306 | ONLINE | +-------------+-------------+--------------+ If the server you are restoring is a primary member, once it has gained synchrony with the group and become  ONLINE , perform the steps described at the end of Restoring a Primary Member to revert the configuration changes you had made to the server before you started it. The member has now been restored to the group as a new member. Restoring Persisted System Variables.  mysqlbackup  does not provide support for backing up or preserving Section 5.1.9.3, “Persisted System Variables” —the file  mysqld-auto.cnf  is not included in a backup. To start the restored member with its persisted variable settings, you need to do one of the following: Restoring a Primary Member.   If the restored member is a primary in the group, care must be taken to prevent writes to the restored database during the Group Replication distributed recovery process. Depending on how the group is accessed by clients, there is a possibility of DML statements being executed on the restored member once it becomes accessible on the network, prior to the member finishing its catch-up on the activities it has missed while off the group. To avoid this,  before starting the restored server , configure the following system variables in the server option file: These settings ensure that the member becomes read-only at startup and that the event scheduler is turned off while the member is catching up with the group during the distributed recovery process. Adequate error handling must also be configured on the clients, as they are prevented temporarily from performing DML operations during this period on the restored member. Once the restore process is fully completed and the restored member is in-sync with the rest of the group, revert those changes; restart the event scheduler: Edit the following system variables in the member’s option file, so things are correctly configured for the next startup: This section explains how to secure a group, securing the connections between members of a group, or by establishing a security perimeter using an IP address allowlist. 3764 18.6 Group Replication Security group_replication_start_on_boot=ON super_read_only=OFF event_scheduler=ON mysql>  SET global event_scheduler=ON; group_replication_start_on_boot=OFF super_read_only=ON event_scheduler=OFF Note •Preserve a copy of the  mysqld-auto.cnf  file from the corrupted server, and copy it to the restored server’s data directory. •Copy the  mysqld-auto.cnf  file from another member of the group into the restored server’s data directory, if that member has the same persisted system variable settings as the corrupted member. •After the restored server is started and before you restart Group Replication, set all the system variables manually to their persisted values through a  mysql  client.