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

坏气十足

　　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 6.9 Operating System, but also work with older version of Linux distributions with MySQL 5.x.
　　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.

• Working Linux OS like CentOS 6.9
  
• Master and Slave are CentOS 6.9 Linux Servers.
  
• Master IP Address is: 192.168.0.70.
  
• Slave IP Address is: 192.168.0.71.
  
• Master and Slave are on the same LAN network.
  
• Master and Slave has MySQL version installed.
  
• Master allow remote MySQL connections on port 3306.
  

　　We have two servers, one is Master with IP (192.168.0.70) and other is Slave as (192.168.0.71). We have divided the setup process in two STEPS to make things easier for you, In STEP 1 we will configure Master server and in Phase II with Slave server. Let’s start the replication setup process.
　　STEP 1 【Configure Master Server (192.168.0.70) for Replication】
　　1) Install a MySQL in Master Server　



　　# yum install mysql-server mysql

　　2) Configure a MySQL in Master Server. edit /etc/my.cnf configuration.
　　3) Add the following entries under [mysqld] section and don’t forget to replace "your database name" with database name that you would like to replicate on Slave.　　



　　server-id = 1
　　binlog-do-db=your database name
　　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

　　4) Restart the MySQL service.



　　# /etc/init.d/mysqld restart

　　5) 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 | your database |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
　　mysql> exit;
　　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 root@192.168.1.2:/root/

　　That’s it we have successfully configured Master server, let’s proceed to Step 2 section.


　　STEP 2 【Configure Slave Server (192.168.0.71) for Replication】
　　1) 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
　　2) Configure a MySQL in Slave Server，edit  /etc/my.cnf configuration .



　　server-id = 2
　　master-host=192.168.0.70
　　master-connect-retry=60
　　master-user=slave_user
　　master-password=your password
　　replicate-do-db=your database name
　　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

　　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 192.168.0.70 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='192.168.0.70', MASTER_USER='slave_user', MASTER_PASSWORD='your password';
　　mysql> slave start;
　　mysql> show slave status\G
　　display:



    Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.0.70
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: your database
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)

DONE!!!!
　　参考 https://www.tecmint.com/how-to-setup-mysql-master-slave-replication-in-rhel-centos-fedora/