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====

base on the config cluster document, need to create replicator dbuser on both servers, but i dont know mariadb root password so any suggestion?

below is instruction: 
create replicator dbuser on both servers

    on mail1, login as MariaDB root user, then execute sql commands below:

create user 'replicator'@'%' identified by '12345678';
grant replication slave on *.* to 'replicator'@'%';
SHOW MASTER STATUS;
+--------------------+----------+----------------------------------------------+-------------------------------+
| File               | Position | Binlog_Do_DB                                 | Binlog_Ignore_DB              |
+--------------------+----------+----------------------------------------------+-------------------------------+
| mariadb-bin.000001 |      245 | amavisd,iredadmin,iredapd,roundcubemail,sogo | test,information_schema,mysql |
+--------------------+----------+----------------------------------------------+-------------------------------+

check master status in column File and Position:

    on mail2:

create user 'replicator'@'%' identified by '12345678';
grant replication slave on *.* to 'replicator'@'%';
slave stop;
CHANGE MASTER TO MASTER_HOST = '192.168.1.3', MASTER_USER = 'replicator', MASTER_PASSWORD = '12345678', MASTER_LOG_FILE = 'mariadb-bin.000001', MASTER_LOG_POS = 245;
slave start;
SHOW MASTER STATUS;
+--------------------+----------+----------------------------------------------+-------------------------------+
| File               | Position | Binlog_Do_DB                                 | Binlog_Ignore_DB              |
+--------------------+----------+----------------------------------------------+-------------------------------+
| mariadb-bin.000001 |     289 | amavisd,iredadmin,iredapd,roundcubemail,sogo | test,information_schema,mysql |
+--------------------+----------+----------------------------------------------+-------------------------------+

show slave status\G;

    change to your own master status MASTER_LOG_FILE is from File, MASTER_LOG_POS is from Position of master mail1
    check master status for File and Position

Restart MariaDB service:

systemctl restart mariadb

    on mail1, login as MariaDB root user:

slave stop;
CHANGE MASTER TO MASTER_HOST = '192.168.1.4', MASTER_USER = 'replicator', MASTER_PASSWORD = '12345678', MASTER_LOG_FILE = 'mariadb-bin.000001', MASTER_LOG_POS = 289;
slave start;
show slave status\G;
exit;

  Thanks