mysql database replication : How To Step by Step: master -slave replication

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Here we will help you to setup master-slave replication between MySQL servers.

Setup Details:
Master Server: 10.0.10.12
Slave  Server: 10.0.10.18
Database: empmaster

1. Setup MySQL Master Server

  • Create an mysql account on Master server with REPLICATION SLAVE privileges to which replication client will connect to master.
  • Block write statement on all the tables, so not changes made after taking backup.
  • Edit MySQL configuration file and add the following lines under [mysqld] section.
  • Restart master mysql server to changes take effect.
  • Check the current binary log file name (File) and current offset (Position) value using following command.
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl_user'@'10.0.10.18' IDENTIFIED BY 'secretpassword';
mysql> FLUSH PRIVILEGES;
mysql> use empmaster;
mysql> FLUSH TABLES WITH READ LOCK;
mysql> exit;
# vim /etc/my.cnf
[mysqld]
log-bin=mysql-bin
binlog-do-db=empmaster
server-id=1
innodb_flush_log_at_trx_commit=1
sync_binlog=1

# service mysqld restart
mysql > SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000002 |      107 | empmaster         |                  |
+------------------+----------+--------------+------------------+

The above output is showing that the current binary file is using mysql-bin.000002 and offset value is107. Note down these values to use on slave server.

  • Take a backup of database and copy it to slave mysql server.
  • After completing backup remove the READ LOCK from tables, So that changes can be made.
  • Edit salve mysql configuration file and add following values under [mysqld] section.
# mysqldump -u root -p empmaster > empmaster.sql
# scp empmaster.sql 10.0.10.18:/opt/
mysql> UNLOCK TABLES;

2. Setup MySQL Slave Server

# vim /etc/my.cnf
[mysqld]
server-id=2
replicate-do-db=empmaster

server-id always be an non zero numeric value. These value will never be similar with other master and slave servers.

  • Restart mysql slave server, If you had already configured replication use –skip-slave-start in start to not to immediate connect to master server.
  • Restore database backup taken from master server.
  • Setup option values on slave server using following command.
  • Finally start the slave thread
  • Check the status of slave server.
# /etc/init.d/mysqld restart
# mysql -u root -p empmaster < empmaster.sql
mysql>  CHANGE MASTER TO MASTER_HOST='10.0.10.12',
    -> MASTER_USER='repl_user',
    -> MASTER_PASSWORD='secretpassword',
    -> MASTER_LOG_FILE='mysql-bin.000002',
    -> MASTER_LOG_POS=107;
mysql> SLAVE START;
mysql> show slave status \G

*************************** 1. row ***************************
               Slave_IO_State:
                  Master_Host: 192.168.1.15
                  Master_User: repl_user
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000002
          Read_Master_Log_Pos: 107
               Relay_Log_File: mysqld-relay-bin.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: mysql-bin.000002
             Slave_IO_Running: No
            Slave_SQL_Running: No
              Replicate_Do_DB: empmaster
          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: 107
              Relay_Log_Space: 107
              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: NULL
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error:
               Last_SQL_Errno: 0
               Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
             Master_Server_Id: 1
1 row in set (0.00 sec)
mysql>

MySQL Master-slave Replication has been configured successfully on your system and in working mode.

 

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