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Setting up replication in MariaDB 11 version

13 Jun 2024

What is MariaDB Replication?

MariaDB replication is the process of automatically transferring data changes that occur on a master database server to one or more slave database servers. This allows for maintaining duplicate copies of data, providing the following benefits:

  • Data distribution and load balancing
  • Data backup and recovery
  • Failover and high availability
  • Support for data warehousing and data mining analysis tasks

Overview of the Replication Process

  1. The master server records SQL statements in the binary log.
  2. The I/O thread of the slave server reads the binary log events from the master and records them in the relay log.
  3. The SQL thread of the slave executes the relay log events to replicate the data.

Replication Setup Process

  1. Master server configuration
    1. Enable binary logging
    2. Assign a unique server ID
  2. Configure the master server information on the slave server
  3. Start the replication process on the slave

After this, data changes on the master server are automatically replicated to the slave. You can monitor the replication status and perform failover if necessary.

MariaDB Server Configuration

  • server-id: Sets the unique identifier for the server. Used to identify each server when operating multiple servers.
  • log_bin: Specifies the path to the binary log file. Used to log database changes and track the state of the database.
  • expire_logs_days: Sets the number of days the binary log files are retained. Previous log files are automatically deleted after the specified number of days.
  • max_binlog_size: Sets the maximum size of the binary log file. A new log file is created when the file size exceeds the specified size.

Configuration

MariaDB 11 version does not have the mysql command, instead, it is executed with the mariadb command.

1. Master

1.1 Configuration

Configure /etc/mysql/mariadb.conf.d/50-server.cnf. It works as described for each setting above.

server-id              = 1
log_bin                = /var/log/mysql/mysql-bin.log
expire_logs_days       = 10
max_binlog_size        = 100M

1.2 Create an account for the slave

Run mariadb -u root -p to create an account to be used on the slave.

grant replication slave on *.* to 'slave_db' @'%' identified by 'slave_password';

Restart MariaDB afterwards.

service mariadb restart #필요시 sudo

**1.3 check binay log **

show master status;

MariaDB [(none)]> show master status;

+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000002 |      342 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.000 sec)

Save the File and Position values. The Position value will change every time there is a change in the master database.

Slave

1.1 Configuration

Configure /etc/mysql/mariadb.conf.d/50-server.cnf.

server-id              = 2

Restart MariaDB.

service mariadb restart # if necessary sudo

1.2 set master infomation

Assume that the IP of the server where the master is running is 192.168.0.100 and the port is 3306.

Run show master status; and put the obtained value FILE as MASTER_LOG_FILE, Position as MASTER_LOG_POS.

CHANGE MASTER TO MASTER_HOST = "192.168.0.100",
MASTER_USER = "slave_db",
MASTER_PASSWORD = "slave_password",
MASTER_PORT = 3306,
MASTER_LOG_FILE = "mysql-bin.000002",
MASTER_LOG_POS = 342;

If it is applied correctly, start the slave.

start slave;

Test

If you connect to the master and execute the following, you can confirm that it is applied the same way on the slave.

CREATE DATABASE foo;
USE foo;
CREATE TABLE users (name VARCHAR(255));
INSERT INTO users (name) VALUES ('Alice');
INSERT INTO users (name) VALUES ('Adam');

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