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MySQL master-slave replication (one master and one slave)
What is master-slave replication
MySQL master-slave replication means that data can be copied from the master node of a MySQL database server to one or more slave nodes. The master node records all write operations and records these write operations in the binary log. The slave node obtains and applies these binary logs by connecting to the master node, thereby achieving data replication.
MySQL uses asynchronous replication by default, which means that after the master node performs write operations, it does not wait for the slave nodes to apply these operations, but immediately returns them to the client. The slave node asynchronously receives and applies the binary log of the master node to maintain consistency with the master node data.
The slave node can replicate all databases in the master node, or you can choose to replicate specific databases or specific tables. By configuring the parameters of the master node and slave node, you can make corresponding settings.
The principle of master-slave replication
The master server records data changes and writes these changes to the binary log
The slave server will regularly check the master's binary log. If a change is found, it will request the master to send a binary event. The master will open an I/O thread, send the binary event to the slave and save it to the local relay log of the slave node.
The slave node will start the SQL thread, read the binary log from the relay log and replay it locally to make the data of the slave node consistent with the master node.
Finally, the I/O thread and SQL thread will go to sleep and wait for the next time they are awakened
Advantages of master-slave replication
-
Improved availability: When the master node fails, it can quickly switch to the slave node to ensure continuous availability of the database.
-
Load balancing: Distribute write requests to the master node and read operations to the slave nodes to reduce the load on the master node and improve performance.
-
Data backup: slave nodes can be used as backups to the master node to prevent data loss
Preparation
Prepare two servers and install MySQL separately.
| IP | type |
|---|---|
| 192.168.200.10 | master node |
| 192.168.200.20 | slave node |
Step 1: Modify the hostname
Modify the host name of 192.168.200.10 to master
Modify the host name of 192.168.200.20 slave
[root@master ~]# hostname -I
192.168.200.10
[root@localhost ~]# hostnamectl set-hostname master
[root@localhost ~]# bash
[root@master ~]#
[root@slave ~]# hostname -I
192.168.200.20
[root@localhost ~]# hostnamectl set-hostname slave
[root@localhost ~]# bash
[root@slave ~]#
Step 2: Install using yum
[root@master ~]# yum install -y mariadb-server mariadb
[root@slave ~]# yum install -y mariadb-server mariadb
Step 4: Start the mysql service and set it to start automatically at boot
[root@master ~]# systemctl enable mariadb --now
[root@slave ~]# systemctl enable mariadb --now
# 查看状态
[root@slave ~]# systemctl status mariadb
[root@slave ~]# systemctl status mariadb
Step 5: Check to see if the port is exposed
[root@master ~]# netstat -tlnp |grep 3306
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 15802/mysqld
[root@slave ~]# netstat -tlnp |grep 3306
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN 15991/mysqld
Step 6: Initialize the database and test login
[root@master ~]# mysql_secure_installation
[root@slave ~]# mysql_secure_installation
[root@master ~]# mysql -uroot -p000000
MariaDB [(none)]> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '000000';flush privileges;
# root 用户授予所有数据库的所有权限，并设置密码为 '000000'
MariaDB [(none)]> exit;
[root@slave ~]# mysql -uroot -p000000
MariaDB [(none)]> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '000000';flush privileges;
MariaDB [(none)]> exit;
Step 7: Firewall releases port 3306
[root@master ~]# firewall-cmd --zone=public --add-port=3306/tcp --permanent && firewall-cmd --reload
success
success
[root@slave ~]# firewall-cmd --zone=public --add-port=3306/tcp --permanent && firewall-cmd --reload
success
success
Connect in SQLyog
Configure the main database Master
Modify the configuration file of the MySQL database
[root@master ~]# vim /etc/my.cnf
[mysqld]
# 添加如下两行信息
server-id=10
log_bin
Restart mysql service
[root@master ~]# systemctl restart mariadb
Create an account for copying and authorize it
Authorize the slave node to perform master-slave replication. After executing this command, the slave node user csqwill be granted replication permissions and can use the password 000000to connect to the master node for replication.
MariaDB [(none)]> grant replication slave on *.* to 'csq'@'192.168.200.%' identified by '000000';
Login mysql
Display a list of binary log files on the master node
记住下面的Log_name 和File_size，配置从数据库要用
MariaDB [(none)]> show master logs;
+--------------------+-----------+
| Log_name | File_size |
+--------------------+-----------+
| mariadb-bin.000001 | 398 |
+--------------------+-----------+
# Log_name 列显示二进制日志文件的名称
# File_size 列显示二进制日志文件的大小
Configure slave database Slave
Modify mysql database configuration file
[root@slave ~]# vim /etc/my.cnf
[mysqld]
# 添加如下信息
server-id=20
Restart mysql service
[root@slave ~]# systemctl restart mariadb
Login mysql
Configure information to connect to the main database
# 因为配置主数据库的信息参数有很多当你忘记的时候可以查看如下命令
mysql> help change master to;
We can copy and modify it slightly
这里要设置刚刚创建的用户账号信息，以及主数据库的IP
MariaDB [(none)]> CHANGE MASTER TO
-> MASTER_HOST='192.168.200.10',
-> MASTER_USER='csq',
-> MASTER_PASSWORD='000000',
-> MASTER_PORT=3306,
-> MASTER_LOG_FILE='mariadb-bin.000001',
-> MASTER_LOG_POS=398;
# MASTER_LOG_FILE 和 MASTER_LOG_POS
# 这两个参数就是指定主数据库的二进制日志文件名称和位置
# 从节点可以确定从哪个位置开始复制数据
Start the master-slave replication process on the slave node.
MariaDB [(none)]> start slave;
# 执行该命令后，从节点将开始连接主节点，并开始复制主节点上的二进制日志
Check the status of the slave database
MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.200.10
Master_User: csq
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mariadb-bin.000001
Read_Master_Log_Pos: 398
Relay_Log_File: mariadb-relay-bin.000002
Relay_Log_Pos: 531
Relay_Master_Log_File: mariadb-bin.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
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: 398
Relay_Log_Space: 827
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:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 10
test
Master database creates a database CSQ
MariaDB [(none)]> create database CSQ;
View from database
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| CSQ |
| mysql |
| performance_schema |
+--------------------+
SQLyog view
Completed