Step for MySQL master to master replication
• First, install MariaDB on both the CentOS 7 based servers.
• Command:
#sudo yum install mariadb-server
#sudo systemctl start mariadb
#sudo systemctl enable mariadb
#sudo systemctl status mariadb
#sudo mysql_secure_installation (press enter for the root password for the first time when it asks and then provide your own password to MySQL)
• Machines to explain the procedure.
Master1 IP: 192.168.1.25
Master2 IP: 192.168.1.26
• Configuration Procedure:
Master1
• In the master1 terminal, check the status of MariaDB.
#sudo systemctl status mariadb
• Open my.cnf file and add the following statement to the file. Save and exit from the file.
#vi /etc/my.cnf
server-id=10
log-bin=mysql-bin
• Restart the MariaDB service by running the following command.
#sudo systemctl restart mariadb
• After login to MySQL we are going to create a user.
#mysql –u root –p
#MariaDB [Linux]> create user ‘reply’@’%’ identified by ‘12345’;(here reply is a user and 12345 is password)
#MariaDB [Linux]> grant replication slave on *.* to ‘reply’@’%’ identified by ‘12345’;
#MariaDB [Linux]> flush privileges;
#MariaDB [Linux]> flush tables with read lock;
#MariaDB [Linux]> show master status; (it will show you the master log file and master position)
#MariaDB [Linux]>exit
• Take the MySQL dump from master1 terminal and execute the following command.
#mysqldump mysql –u root -p> mysql-db.sql
#rsync -Pavzxl mysql-db.sql [email protected]:/root/
Master2
• In the master 2 terminal, check the status of MariaDB.
#sudo systemctl status mariadb
• Open my.cnf file and add the following statement to the file. Save and exit from the file.
#vi /etc/my.cnf
server-id=20
log-bin=mysql-bin
• Restart the MariaDB service by running the following command.
#systemctl restart mariadb.service
• Now inject the MySQL dump file into the master2 database.
#mysql mysql -u root -p < mysql-db.sql
• After dumping, open the MySQL shell and do the replication configuration as shown below.
#mysql –u root –p
#MariaDB [Linux]> stop slave;
#MariaDB [Linux]> change master to master_host=’192.168.1.25′, master_user=’reply’, master_password=’12345′, master_log_file=’mysql-bin.000002′, master_log_pos=566; (check the master log file and master log position of master1)
#MariaDB [Linux]> start slave;
#MariaDB [Linux]> show process list;
• Check the slave status by using the command as shown below.
#MariaDB [Linux]> show slave status;
#MariaDB [Linux]> exit
• Restart the MariaDB service by running the following command.
#systemctl restart mariadb.service
• Go to the master and check the master status using the command as shown below.
# mysql –u root –p
#MariaDB [Linux]> show master status; (it will show you the master log file and master position)
Master1
• In the master terminal, check the established connection using the netstat command.
# netstat -natp | egrep -i established.*mysql
• Open MySQL and check the process list and also configure the replication settings.
#mysql –u root –p
#MariaDB [Linux]> unlock tables;
#MariaDB [Linux]> show processlist;
#MariaDB [Linux]> stop slave;
#MariaDB [Linux]> change master to master_host=’192.168.1.26′,
master_user=’reply’,master_password=’12345′, master_log_file=’mysql-bin.000004′, master_log_pos=245;
#MariaDB [Linux]> start slave;
#MariaDB [Linux]> show slave status;
• Replication configuration is done. Now checking the Replication process.
Master1
• I have created one database named Linux.
#MariaDB [(none)]> create database Linux;
#MariaDB [(none)]> use Linux;
• Create a table for the newly created database.
# MariaDB [Linux]> create table Distribution (Distro varchar(25) NOT NULL);
• Insert some values into the newly created table.
# MariaDB [Linux]> insert into Distribution values(‘REDHAT’);
• The table and the database has been created successfully. List the table from the database.
# MariaDB [Linux]> select * from Distribution;
Master2
• In master 2, login to MySQL and list the databases.
# MariaDB [(none)]> show databases;
• Now the database which is created in master1 is replicated in master2. Use the database and list the table.
# MariaDB [(none)]> use Linux ;
# MariaDB [Linux]> show tables;
• Select and list the table from the selected database.
# MariaDB [Linux]> select * from Distribution;
• Insert some values into that table and list the table’s values the updated values are shown. Now the replication between master-master is working successfully.
# MariaDB [Linux]> insert into Distribution values (‘Ubuntu’);
# MariaDB [Linux]> select * from Distribution;
Master1
• Again go to the master1 terminal, now select and list the tables to check the replication process. If the updated value from master 2 is shown, then the replication process is done.
#mysql –u root –p
# MariaDB [Linux]> select * from Distribution;
Conclusion
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Frequently Asked Questions
Q1. How does master master replication work in MySQL?
Replication relies on three threads per master/slave connection: one on the master and two on the slaves. The slave server begins this thread when you issue START SLAVE, and it connects to the master and requests a copy of the master’s binary log.
Q2. What are the three replication strategies?
- Strategy 1: Log-Based Data Replication.
- Strategy 2: Full Table Data Replication.
- Strategy 3: Key-Based Incremental Data Replication.
Q3. What are the two types of replications?
There are two types of replication exist: direct and conceptual.
