How to set up MySQL master-slave replication

This article introduces to you about setting up master-slave replication between MySQL servers. Let’s take a look at the specific content.

Setting details:

Master server: 192.168.1.10

Slave server: 192.168.1.20

Database: mydb

1. Set up the MySQL main server

Create a server with REPLICATION SLAVE permissions on the main server mysql account, the replication client will connect to the master.

mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl_user'@'192.168.1.20' IDENTIFIED BY 'secretpassword';
mysql> FLUSH PRIVILEGES;

Have block write statements on all tables, so do not make changes after backup.

mysql> use mydb;
mysql> FLUSH TABLES WITH READ LOCK;
mysql> exit;

Edit the mysql configuration file and add the following code under the [mysqld] section.

# vim /etc/my.cnf

[mysqld]
log-bin=mysql-bin
binlog-do-db=mydb
server-id=1
innodb_flush_log_at_trx_commit=1
sync_binlog=1

Restart the master mysql server for the changes to take effect.

# service mysqld restart

Use the following command to check the current binary log file name (File) and current offset (Position) value.

mysql > SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000002 |      107 | mydb         |                  |
+------------------+----------+--------------+------------------+

The above output shows that the current binary file is using mysql-bin.000002 with an offset value of 107. Note these values ​​for use on the slave server.

Back up the database and copy it to slave mysql server.

# mysqldump -u root -p mydb > mydb.sql
# scp mydb.sql 192.168.1.20:/opt/

After completing the backup, remove the READ LOCK from the table so that changes can be made.

mysql> UNLOCK TABLES;

2. Set up MySQL Slave Server

Edit the salve mysql configuration file and add the following values ​​under the [mysqld] section.

# vim /etc/my.cnf

[mysqld]
server-id=2
replicate-do-db=mydb

server-id is always a non-zero value. These values ​​will never be similar to other masters and slaves.

Restart the mysql slave server. If you have configured replication, please use -skip-slave-start when starting. Do not connect to the master server immediately.

# /etc/init.d/mysqld restart

Use the following commands to set option values ​​on the slave server.

mysql>  CHANGE MASTER TO MASTER_HOST='192.168.1.10',
    -> MASTER_USER='repl_user',
    -> MASTER_PASSWORD='secretpassword',
    -> MASTER_LOG_FILE='mysql-bin.000002',
    -> MASTER_LOG_POS=107;

Finally start the slave thread

mysql> SLAVE START;

Check the status of the slave server.

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: mydb
          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 successfully configured on your system and work mode.

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