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## Group Replication Settings 

At this point the option file ensures that the server is configured and is instructed to instantiate the replication infrastructure under a given configuration. The following section configures the Group Replication settings for the server. 

plugin_load_add=’group_replication.so’ group_replication_group_name="aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa" group_replication_start_on_boot=off group_replication_local_address= "s1:33061" group_replication_group_seeds= "s1:33061,s2:33061,s3:33061" group_replication_bootstrap_group=off 

• plugin-load-add  adds the Group Replication plugin to the list of plugins which the server loads at startup. This is preferable in a production deployment to installing the plugin manually. 

•Configuring group_replication_group_name  tells the plugin that the group that it is joining, or creating, is named "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa". 

The value of group_replication_group_name  must be a valid UUID. You can use SELECT UUID()  to generate one. This UUID forms part of the GTIDs that are used when transactions received by group members from clients, and view change events that are generated internally by the group members, are written to the binary log. 

•Configuring the group_replication_start_on_boot  variable to off  instructs the plugin to not start operations automatically when the server starts. This is important when setting up Group Replication as it ensures you can configure the server before manually starting the plugin. Once the member is configured you can set group_replication_start_on_boot  to on  so that Group Replication starts automatically upon server boot. 

•Configuring group_replication_local_address  sets the network address and port which the member uses for internal communication with other members in the group. Group Replication uses this address for internal member-to-member connections involving remote instances of the group communication engine (XCom, a Paxos variant). 

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## Important 

The group replication local address must be different to the host name and port used for SQL client connections, which are defined by MySQL Server’s hostname  and port  system variables. It must not be used for client applications. It must be only be used for internal communication between the members of the group while running Group Replication. 

The network address configured by group_replication_local_address  must be resolvable by all group members. For example, if each server instance is on a different machine with a fixed network address, you could use the IP address of the machine, such as 10.0.0.1. If you use a host name, you must use a fully qualified name, and ensure it is resolvable through DNS, correctly configured /etc/ hosts  files, or other name resolution processes. From MySQL 8.0.14, IPv6 addresses (or host names that resolve to them) can be used as well as IPv4 addresses. A group can contain a mix of members using IPv6 and members using IPv4. For more information on Group Replication support for IPv6 networks and on mixed IPv4 and IPv6 groups, see Section 18.5.5, “Support For IPv6 And For Mixed IPv6 And IPv4 Groups” . 

The recommended port for group_replication_local_address  is 33061. group_replication_local_address  is used by Group Replication as the unique identifier for a group member within the replication group. You can use the same port for all members of a replication group as long as the host names or IP addresses are all different, as demonstrated in this tutorial. 

