How to Setup MySQL (Master-Slave) Replication in RHEL, CentOS, Fedora

The following tutorial aims to provide you a simple step-by-step guide for setting up MySQL (Master-Slave) Replication in RHEL 6.3/6.2/6.1/6/5.8, CentOS 6.3/6.2/6.1/6/5.8 and Fedora 17,16,15,14,13,12 using latest MySQL version. This guide is specially written for CentOS 6.3 Operating System, but also work with older version of Linux distributions with MySQL 5.x.

UPDATE: If you’re looking for MariaDB Master-Slave Replication under CentOS/RHEL 7 and Debian 8 and it’s derivatives such as Ubuntu, follow this guide Setup MariaDB Master-Slave Replication.

mysql replication in Linux

MySQL Master-Slave Replication in RedHat / CentOS / Fedora

The MySQL Replication is very useful in terms of Data Security, Fail-over Solution, Database Backup from Slave, Analytics etc. We use the following things to carry the replication process. In your scenario it would be different.

  1. Working Linux OS like CentOS 6.3, RedHat 6.3 or Fedora 17
  2. Master and Slave are CentOS 6.3 Linux Servers.
  3. Master IP Address is: 192.168.1.1.
  4. Slave IP Address is: 192.168.1.2.
  5. Master and Slave are on the same LAN network.
  6. Master and Slave has MySQL version installed.
  7. Master allow remote MySQL connections on port 3306.

We have two servers, one is Master with IP (192.168.1.1) and other is Slave as (192.168.1.2). We have divided the setup process in two phases to make things easier for you, In Phase I we will configure Master server and in Phase II with Slave server. Let’s start the replication setup process.

Phase I: Configure Master Server (192.168.1.1) for Replication

In Phase I, we will see the installation of MySQL, setting up Replication and then verifying replication.

Install a MySQL in Master Server

First, proceed with MySQL installation using YUM command. If you already have MySQL installation, you can skip this step.

# yum install mysql-server mysql
Configure a MySQL in Master Server

Open my.cnf configuration file with VI editor.

# vi /etc/my.cnf

Add the following entries under [mysqld] section and don’t forget to replace tecmint with database name that you would like to replicate on Slave.

server-id = 1
binlog-do-db=tecmint
relay-log = /var/lib/mysql/mysql-relay-bin
relay-log-index = /var/lib/mysql/mysql-relay-bin.index
log-error = /var/lib/mysql/mysql.err
master-info-file = /var/lib/mysql/mysql-master.info
relay-log-info-file = /var/lib/mysql/mysql-relay-log.info
log-bin = /var/lib/mysql/mysql-bin

Restart the MySQL service.

# /etc/init.d/mysqld restart

Login into MySQL as root user and create the slave user and grant privileges for replication. Replace slave_user with user and your_password with password.

# mysql -u root -p
mysql> GRANT REPLICATION SLAVE ON *.* TO 'slave_user'@'%' IDENTIFIED BY 'your_password';
mysql> FLUSH PRIVILEGES;
mysql> FLUSH TABLES WITH READ LOCK;
mysql> SHOW MASTER STATUS;

+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000003 | 11128001 | tecmint		 |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

mysql> quit;

Please write down the File (mysql-bin.000003) and Position (11128001) numbers, we required these numbers later on Slave server. Next apply READ LOCK to databases to export all the database and master database information with mysqldump command.

#  mysqldump -u root -p --all-databases --master-data > /root/dbdump.db

Once you’ve dump all the databases, now again connect to mysql as root user and unlcok tables.

mysql> UNLOCK TABLES;
mysql> quit;

Upload the database dump file on Slave Server (192.168.1.2) using SCP command.

scp /root/dbdump.db [email protected]:/root/

That’s it we have successfully configured Master server, let’s proceed to Phase II section.

Phase II: Configure Slave Server (192.168.1.2) for Replication

In Phase II, we do the installation of MySQL, setting up Replication and then verifying replication.

Install a MySQL in Slave Server

If you don’t have MySQL installed, then install it using YUM command.

# yum install mysql-server mysql
Configure a MySQL in Slave Server

Open my.cnf configuration file with VI editor.

# vi /etc/my.cnf

Add the following entries under [mysqld] section and don’t forget to replace IP address of Master server, tecmint with database name etc, that you would like to replicate with Master.

server-id = 2
master-host=192.168.1.1
master-connect-retry=60
master-user=slave_user
master-password=yourpassword
replicate-do-db=tecmint
relay-log = /var/lib/mysql/mysql-relay-bin
relay-log-index = /var/lib/mysql/mysql-relay-bin.index
log-error = /var/lib/mysql/mysql.err
master-info-file = /var/lib/mysql/mysql-master.info
relay-log-info-file = /var/lib/mysql/mysql-relay-log.info
log-bin = /var/lib/mysql/mysql-bin

Now import the dump file that we exported in earlier command and restart the MySQL service.

# mysql -u root -p < /root/dbdump.db
# /etc/init.d/mysqld restart

Login into MySQL as root user and stop the slave. Then tell the slave to where to look for Master log file, that we have write down on master with SHOW MASTER STATUS; command as File (mysql-bin.000003) and Position (11128001) numbers. You must change 192.168.1.1 to the IP address of the Master Server, and change the user and password accordingly.

# mysql -u root -p
mysql> slave stop;
mysql> CHANGE MASTER TO MASTER_HOST='192.168.1.1', MASTER_USER='slave_user', MASTER_PASSWORD='yourpassword', MASTER_LOG_FILE='mysql-bin.000003', MASTER_LOG_POS=11128001;
mysql> slave start;
mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.1.1
                  Master_User: slave_user
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 12345100
               Relay_Log_File: mysql-relay-bin.000002
                Relay_Log_Pos: 11381900
        Relay_Master_Log_File: mysql-bin.000003
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes
              Replicate_Do_DB: tecmint
          Replicate_Ignore_DB:
           Replicate_Do_Table:
       Replicate_Ignore_Table:
      Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
                   Last_Errno: 0
                   Last_Error:
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 12345100
              Relay_Log_Space: 11382055
              Until_Condition: None
               Until_Log_File:
                Until_Log_Pos: 0
           Master_SSL_Allowed: No
           Master_SSL_CA_File:
           Master_SSL_CA_Path:
              Master_SSL_Cert:
            Master_SSL_Cipher:
               Master_SSL_Key:
        Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error:
               Last_SQL_Errno: 0
               Last_SQL_Error:
1 row in set (0.00 sec)

Verifying MySQL Replication on Master and Slave Server

It’s really very important to know that the replication is working perfectly. On Master server create table and insert some values in it.

On Master Server
mysql> create database tecmint;
mysql> use tecmint;
mysql> CREATE TABLE employee (c int);
mysql> INSERT INTO employee (c) VALUES (1);
mysql> SELECT * FROM employee;
+------+
|  c  |
+------+
|  1  |
+------+
1 row in set (0.00 sec)
On Slave Server

Verifying the SLAVE, by running the same command, it will return the same values in the slave too.

mysql> use tecmint;
mysql> SELECT * FROM employee;
+------+
|  c  |
+------+
|  1  |
+------+
1 row in set (0.00 sec)

That’s it, finally you’ve configured MySQL Replication in a few simple steps. More information can be found at MySQL Replication Guide.

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162 Responses

  1. Memmiche says:

    Hello, Thank for this Tutorial, but it doesn’t work for me, I followed all steps, but sadly i can’t find the database that I create on Master in the other one. Please Contact me

  2. umesh says:

    I get following error, how can resolve this issue?

    [[email protected] ~]# mysql -u root -p < /root/dbdump.db
    error: Found option without preceding group in config file: /etc/my.cnf at line: 11
    Fatal error in defaults handling. Program aborted
    
  3. vish says:

    After changing slave server changes on my.cnf and restore the required database. Then slave server mysql service is not starting.

  4. satyapal Kumar says:

    Hi,

    MySQL service failed on Slave node when trying to configure CentOS 6.3 with MYSQL Server version: 5.7.22-log MySQL Community Server (GPL).

  5. sujith says:

    Hi, I am getting error, status show connecting and last i/o shows error connecting to master ip address.

    Please help me..

  6. Russell Scattone says:

    So like the simplicity of the setup. However it did not work and was frustrating as everything seemed to be set up correctly. Took some time to find the problem is due to the “binlog-do-db“.

    Problem for me was there was a “test” DB and even though I was creating a “test” table in different DB it wasn’t being replicated. Read this post about why it’s dangerous: https://www.percona.com/blog/2009/05/14/why-mysqls-binlog-do-db-option-is-dangerous/ . Other than that thanks for your contributions

  7. prashant kumar says:

    my master slave was running perfectly but once master got shutdown due to power failure (breakdown ) and it stop replication how to overcome this situation ? or restart replication with minimum downtime

    • Ravi Saive says:

      @Prashant,

      Never faced such power failure issues, but I think there nothing to worry, once you master started its automatically starts replicating to slave..

  8. Tudor says:

    To put master host and so on slave in /etc/my.cnf is officially deprecated.

    Instead run in mysql

    Extract from official website
    “2.2.5.2 Setting the Master Configuration on the Slave

    To set up the slave to communicate with the master for replication, configure the slave with the necessary connection information. To do this, execute the following statement on the slave, replacing the option values with the actual values relevant to your system:

    mysql> CHANGE MASTER TO
        ->     MASTER_HOST='master_host_name',
        ->     MASTER_USER='replication_user_name',
        ->     MASTER_PASSWORD='replication_password',
        ->     MASTER_LOG_FILE='recorded_log_file_name',
        ->     MASTER_LOG_POS=recorded_log_position;
    
  9. Arun Mohan says:

    I got the same error..

    ERROR 1794 (HY000) at line 22: Slave is not configured or failed to initialize properly. You must at least set –server-id to enable either a master or a slave. Additional error messages can be found in the MySQL error log

  10. James says:

    mysql -u root -p < /root/dbdump.db
    Enter password:
    ERROR 1794 (HY000) at line 22: Slave is not configured or failed to initialize properly. You must at least set –server-id to enable either a master or a slave. Additional error messages can be found in the MySQL error log.

    I got this when I tried to do the restore on the slave.

    • Ravi Saive says:

      @James,

      Have you properly configured Slave server? added correct server-id in slave my.cnf file? please check and confirm..

      • Gulab Pasha says:

        Hi Ravi,

        I have followed your article its good, I have done the configuration in Master no issue but getting an error on slave while importing DB

        ERROR 1794 (HY000) at line 22: Slave is not configured or failed to initialize properly. You must at least set –server-id to enable either a master or a slave. Additional error messages can be found in the MySQL error log.

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