MariaDB Replication: Overview and Setup

MariaDB replication is a process by which data from one MariaDB database server (the master) is copied to one or more MariaDB database servers (the slaves). Replication is a fundamental feature of MariaDB that provides high availability, scalability, and data redundancy. Here's an overview of MariaDB replication and how to set it up:

1. Replication Terminology:

   - Master: The MariaDB server that serves as the source of the replication process. It contains the original data that needs to be replicated to one or more slave servers.

   

   - Slave: A MariaDB server that replicates data from the master. Multiple slaves can replicate data from the same master.

   

   - Binary Log: The binary log contains a record of all changes to the master's databases. It serves as the source of data for replication.

   

   - Replication Channel: A communication channel between the master and each slave, used for transmitting replication events.

2. Replication Modes:

   - Asynchronous Replication: The default mode in MariaDB replication, where changes are propagated from the master to the slave(s) without waiting for confirmation from the slave(s) that the changes have been applied.

   

   - Semi-Synchronous Replication: A mode where the master waits for at least one slave to acknowledge receipt of a replication event before considering the event committed. This mode provides stronger data consistency guarantees compared to asynchronous replication.

3. Setting Up Replication:

   Here's a high-level overview of the steps to set up replication:

   - Configure Master Server:

     1. Enable binary logging in the MariaDB configuration file (my.cnf):

        

        [mysqld]

        log-bin=master-bin

        server-id=1

        

        log-bin specifies the binary log filename prefix, and server-id uniquely identifies the master server.

        

     2. Create a replication user with appropriate privileges:

        sql

        CREATE USER 'repl_user'@'slave_ip' IDENTIFIED BY 'password';

        GRANT REPLICATION SLAVE ON *.* TO 'repl_user'@'slave_ip';

        

   - Backup and Restore Master Data (Optional):

     If you're setting up replication on an existing database, you may want to take a backup of the master's data and restore it on the slave(s) before starting replication.

   - Configure Slave Server(s):

     1. Enable binary logging and set a unique server-id in the MariaDB configuration file.

     

     2. Stop the MariaDB service, copy the master's data to the slave, and start the MariaDB service.

   - Start Replication:

     On the slave server, issue the following SQL command to start the replication process:

     sql

     CHANGE MASTER TO

         MASTER_HOST='master_ip',

         MASTER_USER='repl_user',

         MASTER_PASSWORD='password',

         MASTER_LOG_FILE='master-bin.XXXXXX',

         MASTER_LOG_POS=XXX;

     START SLAVE;

     

     Replace master_ip, repl_user, password, master-bin.XXXXXX, and XXX with the appropriate values.

4. Monitoring Replication:

   You can monitor the replication status using various MariaDB commands and tools, such as SHOW SLAVE STATUS, SHOW MASTER STATUS, and monitoring tools like MariaDB Monitor.

By following these steps, you can set up replication between a master and one or more slave servers in a MariaDB environment, providing data redundancy and scalability for your database system.