How to setup MySQL replication on CentOS
In this tutorial we will show you how to setup basic MySQL replication on two CentOS 7 servers, but the same steps should work on all RPM based systems. We will use two test CentOS 7 virtual servers for this tutorial with the following IP addresses:
Login to the master server as user root
and install MySQL server if it is not already installed
yum install mysql-server mysql
Start the MySQL server and enable it to start at boot time
systemctl start mysql systemctl enable mysql
Next, open the MySQL configuration file with a text editor and add the following lines
server-id = 1 binlog-do-db=database relay-log = mysql-relay-bin relay-log-index = mysql-relay-bin.index log-bin = mysql-bin
Don’t forget to replace ‘database‘ with the actual name of the database that you want to replicate to the slave server.
Save the configuration file and restart the MySQL server for the changes to take effect
systemctl restart mysql
Login to the MySQL server as user root and create a user that will be used by the slave
mysql -u root -p
mysql> GRANT REPLICATION SLAVE ON *.* TO 'slaveuser'@'%' IDENTIFIED BY 'PASSWORD' mysql> FLUSH PRIVILEGES; mysql> FLUSH TABLES WITH READ LOCK; mysql> SHOW MASTER STATUS; mysql> SHOW MASTER STATUS; +------------------+----------+--------------+------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | +------------------+----------+--------------+------------------+ | mysql-bin.000001 | 245 | database | | +------------------+----------+--------------+------------------+ 1 row in set (0.00 sec) mysql> exit
We will need the master’s coordinates that are going to be used for the slave server, so write them down.
Replace ‘PASSWORD‘ with an actual strong password.
Now, if the database you want to replicate is not empty, create a dump from the database
mysqldump -u root -p --master-data database > /root/database.sql
and transfer the dump file to the slave server
rsync -Waq -e ssh /root/database.sql 123.456.789.2:/root
Next step is to configure the slave server. Login to the slave server via SSH as user root and install MySQL server as we did on the master server.
After the MySQL server is installed and started, open its configuration file and add the following lines:
server-id = 2 master-host=123.456.789.1 master-connect-retry=60 master-user=slaveuser master-password=PASSWORD replicate-do-db=database relay-log = mysql-relay-bin log-bin = mysql-bin
Save the file and restart the MySQL server for the changes to change effect.
systemctl restart mysql
Import the MySQL dump file we created on the master server
mysql -u root -p < /root/database.sql
Login to MySQL as user root stop the slave and configure it where to look for the ‘master log file’
mysql -u root -p
mysql> slave stop; mysql> CHANGE MASTER TO MASTER_HOST='123.456.789.1', MASTER_USER='slaveuser', MASTER_PASSWORD='PASSWORD', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=245; mysql> slave start;
Use the MySQL username and password we created on the master server.
You can check the slave status by executing the following MySQL command:
mysql> show slave status;
*************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 123.456.789.1 Master_User: slaveuser Master_Port: 3306 Master_Log_File: mysql-bin.000001 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: database
If ‘Slave_IO_State‘ reports ‘Waiting for master to send event’ the replication is successful.
That is all. It’s that easy. If you need more information on how to setup a replication master configuration you can find it on MySQL’s official website.
Of course you don’t have to do any of this if you use one of our Linux VPS Hosting services, in which case you can simply ask our expert Linux admins to setup MySQL replication for you. They are available 24×7 and will take care of your request immediately.
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