How to Set Up MySQL Master‑Slave Replication

Preparation: two virtual machines running CentOS 5.5 with identical MySQL versions, IP 192.168.1.101 (master) and 192.168.1.105 (slave).

Replication principle: the master writes all data‑changing operations to a binary log; the slave reads this log and replays the same operations, achieving data consistency.

Step 1 – Enable binary logging on the master

Open the MySQL configuration file ( # vi /etc/my.cnf ) and add the following lines:

log-bin=mysql-bin

binlog_format=mixed

server-id=101

Save and restart MySQL ( # service mysqld restart ). Perform the same changes on the slave, using server-id=105 , then restart MySQL.

Step 2 – Create a replication user on the master

Log into MySQL on the master:

# mysql -u root -p111111

Execute:

GRANT replication slave ON *.* TO 'slave'@'%' IDENTIFIED BY '111111';

Step 3 – Record the master’s binary‑log file and position

Run SHOW MASTER STATUS; on the master and note the values of File and Position . Do not perform further writes to the master before the slave is configured.

Step 4 – Configure the slave

Log into MySQL on the slave:

# mysql -u root -p111111

Stop any existing replication:

STOP SLAVE;

Set the master connection parameters (replace with your actual values):

CHANGE MASTER TO MASTER_HOST='192.168.1.101', MASTER_USER='slave', MASTER_PASSWORD='111111', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=12345;

Start the slave:

START SLAVE;

Step 5 – Verify replication

Execute on the slave:

SHOW SLAVE STATUS\G

If both Slave_IO_Running and Slave_SQL_Running show Yes , the replication is successful; otherwise repeat the previous steps.

Images in the original article illustrate configuration files and command outputs.