Switching the slave from chain replication to master-slave in MySQL


In the world of databases, replication is a key strategy to ensure data consistency, reliability, and availability. MySQL offers multiple replication methods, including chain replication and master-slave replication. While chain replication has its advantages, such as simplicity and low latency, it may not always be the best fit for every scenario. Master-slave replication provides a more robust solution in many cases, with better fault tolerance and easier scalability. In this article, we will explore the process of switching from chain replication to master-slave replication in MySQL, complete with examples and practical tips.

Understanding Chain Replication and Master-Slave Replication

Before diving into the transition process, it’s essential to understand the key differences between chain replication and master-slave replication in MySQL.

Chain Replication

In chain replication, each server in the chain replicates data from its predecessor, ensuring that data is consistent across all servers. The first server in the chain is the primary server, and it receives all write operations. When the primary server processes a write operation, it forwards the operation to the next server in the chain. This process continues until the last server in the chain confirms the write operation.

Master-Slave Replication

In master-slave replication, there is one master server responsible for processing write operations, and multiple slave servers that replicate data from the master. The master server records changes in a binary log, which slave servers use to update their data. Master-slave replication offers better fault tolerance, as it allows for multiple slaves that can take over if the master server fails.

Preparing for the Transition

Before switching from chain replication to master-slave replication, take the following steps to ensure a smooth transition:

Backup Your Data

Always start by taking a complete backup of your data. Use the mysqldump utility to create a consistent snapshot of your database.

Assess Your Current Replication Setup

Identify the servers involved in the chain replication, their roles, and the configuration settings. This information will be crucial during the transition process.

Configuring the Master Server

Follow these steps to configure the master server in your new master-slave replication setup:

Update the Configuration File

Edit the my.cnf (Linux) or my.ini (Windows) configuration file on the master server, adding or modifying the following lines:


Restart the MySQL Service

Restart the MySQL service for the changes to take effect:

sudo service mysql restart

Grant Replication Privileges

Create a user with replication privileges on the master server:

CREATE USER 'repl_user'@'%' IDENTIFIED BY 'repl_password';
GRANT REPLICATION SLAVE ON *.* TO 'repl_user'@'%';

Configuring Slave Servers

For each slave server in your new replication setup, follow these steps:

Update the Configuration File

Edit the my.cnf (Linux) or my.ini (Windows) configuration file on the slave server, adding or modifying the following lines, making sure to replace ‘x’ with a unique server ID:


Restart the MySQL Service

Restart the MySQL service for the changes to take effect:

sudo service mysql restart

Configure the Slave Server

On the slave server, execute the following commands, replacing the appropriate values:


Make sure to replace ‘master_host’, ‘repl_user’, and ‘repl_password’ with the correct values from your master server. Also, adjust the ‘MASTER_LOG_FILE’ and ‘MASTER_LOG_POS’ values based on the output of the SHOW MASTER STATUS; command executed on the master server.

Start the Slave Replication

Start the replication process on the slave server:


Monitoring and Verifying Replication

After setting up master-slave replication, it’s important to monitor the replication process and verify its success.

Check Replication Status

On each slave server, run the following command:


Look for the following lines in the output:

Slave_IO_Running: Yes
Slave_SQL_Running: Yes

These lines indicate that the replication is running correctly.

Verify Data Consistency

Perform test queries on both the master and slave servers to ensure data consistency. For example, if you insert a new record on the master server, it should appear on the slave servers after a short delay.

Troubleshooting and Common Issues

In case you encounter issues during the transition or replication process, refer to the following common problems and their solutions:

Replication Delay

If the slave server is lagging behind the master server, consider optimizing the network connection or increasing the resources available to the MySQL service on the slave server.

Replication Errors

If you encounter replication errors, review the MySQL error log on both the master and slave servers to identify the root cause. Errors may result from issues such as incompatible database configurations or insufficient privileges.


Switching from chain replication to master-slave replication in MySQL may seem daunting, but with careful preparation and attention to detail, it can be a smooth process. By following the steps outlined in this article, you can successfully transition to a more robust and scalable replication setup, ensuring data consistency and reliability for your applications.

Related Articles