Configure Master-Master MySQL Database Replication

What is MySQL Master-Master Replication?

MySQL Master-Master replication adds speed and redundancy for active websites. With replication, two separate MySQL servers act as a cluster. Database clustering is particularly useful for high availability website configurations. Use two separate Linodes to configure database replication, each with private IPv4 addresses.

Note

This guide is written for a non-root user. Commands that require elevated privileges are prefixed with sudo. If you’re not familiar with the sudo command, you can check our Users and Groups guide.

This guide is written for Debian 9 or Ubuntu 18.04.

Install MySQL

1. Use the following commands to install MySQL on each of the Linodes:

   sudo apt-get update
   sudo apt-get upgrade -y
   sudo apt-get install mysql-server mysql-client
   

2. Run the MySQL secure installation command. You will be asked to create a root password. It is recommended you select yes to all of the questions:

   mysql_secure_installation
   

Edit MySQL’s Configuration

1. Edit the /etc/mysql/my.cnf file on each of the Linodes. Add or modify the following values:

   Server 1:

   File: /etc/mysql/my.cnf

   1 2 3 4 5 6 7 8 9 10 11

   [mysqld] server_id = 1 log_bin = /var/log/mysql/mysql-bin.log log_bin_index = /var/log/mysql/mysql-bin.log.index relay_log = /var/log/mysql/mysql-relay-bin relay_log_index = /var/log/mysql/mysql-relay-bin.index expire_logs_days = 10 max_binlog_size = 100M log_replica_updates = 1 auto-increment-increment = 2 auto-increment-offset = 1

   If using MySQL 8.0.25 or earlier, replace log_replica_updates with log_slave_updates (within both Servers 1 and 2). See MySQL documentation for details.

   Server 2:

   File: /etc/mysql/my.cnf

   1 2 3 4 5 6 7 8 9 10 11

   [mysqld] server_id = 2 log_bin = /var/log/mysql/mysql-bin.log log_bin_index = /var/log/mysql/mysql-bin.log.index relay_log = /var/log/mysql/mysql-relay-bin relay_log_index = /var/log/mysql/mysql-relay-bin.index expire_logs_days = 10 max_binlog_size = 100M log_replica_updates = 1 auto-increment-increment = 2 auto-increment-offset = 2

2. Edit the bind-address configuration in order to use the private IP addresses, for each of the Linodes.

   File: /etc/mysql/my.cnf

   1	bind-address = x.x.x.x

3. Once completed, restart the MySQL application:

   sudo systemctl restart mysql
   

Create Replication Users

1. Log in to MySQL on each of the Linodes:

   mysql -u root -p
   

2. Configure the replication users on each Linode. Replace x.x.x.x with the private IP address of the opposing Linode, and password with a strong password:

   GRANT REPLICATION SLAVE ON *.* TO 'replication'@'x.x.x.x' IDENTIFIED BY 'password';
   

3. Run the following command to test the configuration. Use the private IP address of the opposing Linode:

   mysql -u replication -p -h x.x.x.x -P 3306
   

   This command should connect you to the remote server’s MySQL instance.

Configure Database Replication

1. While logged into MySQL on Server 1, query the master status:

   SHOW MASTER STATUS;
   

   Note the file and position values that are displayed:

   mysql> SHOW MASTER STATUS;
   +------------------+----------+--------------+------------------+
   | File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
   +------------------+----------+--------------+------------------+
   | mysql-bin.000001 |      277 |              |                  |
   +------------------+----------+--------------+------------------+
   1 row in set (0.00 sec)
   

2. On Server 2 at the MySQL prompt, set up the replica functionality for that database. Replacex.x.x.x with the private IP from the first server. Also replace the value for source_log_file with the file value from the previous step, and the value for source_log_pos with the position value.

   STOP REPLICA;
   CHANGE REPLICATION SOURCE TO
       source_host='x.x.x.x',
       source_port=3306,
       source_user='replication',
       source_password='password',
       source_log_file='mysql-bin.000001',
       source_log_pos=106;
   START REPLICA;
   

   If you’re using MySQL 8.0.22 or earlier, use the following statements instead, and replace the value for master_log_file with the file value from the previous step, and the value for master_log_pos with the position value. See the MySQL documentation for details.

   STOP SLAVE;
   CHANGE MASTER TO
       master_host='x.x.x.x',
       master_port=3306,
       master_user='replication',
       master_password='password',
       master_log_file='mysql-bin.000001',
       master_log_pos=106;
   START SLAVE;
   

3. On Server 2, query the master status. Again note the file and position values.

   SHOW MASTER STATUS;
   

4. Set the replica database status on Server 1, utilizing similar commands as in step 2. When entering the commands, use the IP address of Server 2 and the file and position values you just collected in the previous step.

5. Test by creating a database and inserting a row:

   Server 1:

   create database test;
   create table test.flowers (`id` varchar(10));
   

   Server 2:

   show tables in test;
   

When queried, you should see the tables from Server 1 replicated on Server 2. Congratulations, you now have a MySQL Master-Master cluster!

More Information

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

• MySQL Reference Manuals