MySQL数据库主从复制(小白的“升级打怪”成长之路)

目录

概述

基础环境设置

网络对时

防火墙与SELinux

配置主从复制

主服务配置

从服务器配置

主从复制常见问题

实战案例


概述


1、master开启二进制日志记录

2、slave开启IO进程,从master中读取二进制日志并写入slave的中继日志

3、slave开启SQL进程,从中继日志中读取二进制日志并进行重放

4、最终,达到slave与master中数据一致的状态,我们称作为主从复制的过程。

基础环境设置

网络对时

主与从主机都需要操作

[root@localhost ~]# cat /etc/chrony.conf | grep -Ev '^$|#'
​
server ntp.aliyun.com iburst    ###添加或者修改
driftfile /var/lib/chrony/drift
makestep 1.0 3
rtcsync
keyfile /etc/chrony.keys
leapsectz right/UTC
logdir /var/log/chrony 
[root@slave1 ~]# timedatectl set-timezone Asia/Shanghai
[root@slave1 ~]# systemctl restart chronyd.service 
​

防火墙与SELinux

主与从主机都需要操作

[root@localhost ~]# systemctl disable --now firewalld
[root@localhost ~]# sed -i 's/SELIUNX=enforcing/SELINUX=disable/' /etc/selinux/config
[root@localhost ~]# setenforce 0

配置主从复制

主服务配置

##修改配置文件
[root@localhost ~]# cat /etc/my.cnf
​
#
# This group is read both both by the client and the server
# use it for options that affect everything
#
[mysqld]
log-bin=mysql-bin
binlog_format="statement"
server-id=11
log-slave-updates=true
[client-server]
​
#
# include all files from the config directory
#
!includedir /etc/my.cnf.d
​
##启动服务
[root@localhost ~]# systemctl enable --now mysqld
#验证配置
[root@localhost ~]# cd /var/lib/mysql/
[root@localhost mysql]# ls
 auto.cnf        client-cert.pem      ibdata1            mysql-bin.000003   mysql_upgrade_info   server-key.pem
 binlog.000001   client-key.pem       ibtmp1             mysql-bin.000004   mysqlx.sock          sys
 binlog.000002   db1                 '#innodb_redo'      mysql-bin.000005   mysqlx.sock.lock     undo_001
 binlog.index    db2                 '#innodb_temp'      mysql-bin.index    performance_schema   undo_002
 c2407          '#ib_16384_0.dblwr'   mysql              mysql.ibd          private_key.pem
 ca-key.pem     '#ib_16384_1.dblwr'   mysql-bin.000001   mysql.sock         public_key.pem
 ca.pem          ib_buffer_pool       mysql-bin.000002   mysql.sock.lock    server-cert.pem
​
​
##创建从主机可以进行访问的用户
mysql> create user slave@'192.168.166.%' identified by '123.com';
​
mysql> grant all on *.* to 'slave'@'192.168.166.%';
###密码插件修改
ALTER USER 'slave'@'192.168.166.%' IDENTIFIED WITH mysql_native_password BY '123.com';
###查看master正在使用的日志文件及日志书写位置
[root@localhost mysql]# mysql
mysql> show master status;
+-------------------+----------+--------------+------------------+
| File              | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+-------------------+----------+--------------+------------------+
| master-bin.000003 |      542 |              |                  |
+-------------------+----------+--------------+------------------+
1 row in set (0.00 sec)
#注意:查看位置完毕后,不要对master做insert、update、delete、create、drop等操作!!!

从服务器配置

##修改配置文件
[root@localhost ~]# cat /etc/my.cnf
relay-log-index=slave-bin.index
server-id=22
##启动服务
[root@localhost ~]# systemctl enable --now mysqld
​
##配置验证,此时没有与主服务器进行连接,所以没有产生对应的relay log
[root@localhost mysql]# ls
aria_log.00000001  aria_log_control  ibdata1  ib_logfile0  ib_logfile1  mysql  mysql.sock  performance_schema  test
##配置从服务器的所属主服务器
[root@localhost mysql]# mysql
mysql> change master to master_host='192.168.158.4',master_user='slave',master_password='123.com',master_log_file='master-bin.000001',master_log_pos=619;
​
##启动slave角色,默认没有配置主从时,所有的mysql节点都是master
mysql> start slave;
##查看slave状态信息
mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for source to send event
                  Master_Host: 192.168.166.230
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 2567
               Relay_Log_File: slave-bin.000004
                Relay_Log_Pos: 1679
        Relay_Master_Log_File: mysql-bin.000005
             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: 2567
              Relay_Log_Space: 2416
              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: 11
                  Master_UUID: 25105bd5-6fd8-11ef-9dae-000c299fb683
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Replica has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 
            Executed_Gtid_Set: 
                Auto_Position: 0
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
       Master_public_key_path: 
        Get_master_public_key: 0
            Network_Namespace: 
1 row in set, 1 warning (0.00 sec)
​
​
#查看数据目录
[root@localhost mysql]# ls
aria_log.00000001  ibdata1      ib_logfile1  mysql       performance_schema  slave-bin.000001  slave-bin.index
aria_log_control   ib_logfile0  master.info  mysql.sock  relay-log.info      slave-bin.000002  test
​

主从复制常见问题

异常:

mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Connecting to source
                  Master_Host: 192.168.166.230
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 2567
               Relay_Log_File: slave-bin.000004
                Relay_Log_Pos: 1679
        Relay_Master_Log_File: mysql-bin.000005
             Slave_IO_Running: Connecting
            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: 2567
              Relay_Log_Space: 2416
              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: 2003
                Last_IO_Error: Error connecting to source 'slave@192.168.166.230:3306'. This was attempt 1/86400, with a delay of 60 seconds between attempts. Message: Can't connect to MySQL server on '192.168.166.230:3306' (113)
               Last_SQL_Errno: 0
               Last_SQL_Error: 
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 11
                  Master_UUID: 25105bd5-6fd8-11ef-9dae-000c299fb683
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: Replica has read all relay log; waiting for more updates
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 240913 04:04:49
     Last_SQL_Error_Timestamp: 
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: 
            Executed_Gtid_Set: 
                Auto_Position: 0
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
       Master_public_key_path: 
        Get_master_public_key: 0
            Network_Namespace: 
1 row in set, 1 warning (0.00 sec)
​

一般情况下,都与网络通信异常有关系。排查防火墙、物理网络连接等。二进制日志文件名或位置错误也会引起IO线程异常。

reset replica;
##用于重置SQL线程对relay log的重放记录!!

实战案例

实现mysql数据库主从复制

两台设备(ip分别为192.168.58.160和192.168.58.161)都安装mysql服务

[root@mysql-slave ~]# yum install -y mysql-server
[root@mysql-slave ~]# systemctl start mysqld

主服务配置

对时

#192.168.58.160
[root@localhost ~]# timedatectl set-timezone Asia/Shanghai
[root@mysql ~]# vim /etc/chrony.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
pool 2.rocky.pool.ntp.org iburst
​
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
##添加修改此字段
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#pool 2.rocky.pool.ntp.org iburst
server ntp.aliyun.com iburst
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
​
​
[root@mysql ~]# systemctl restart chronyd.service 
[root@mysql ~]# hostnamectl set-hostname mysql-master
[root@mysql ~]# bash
[root@mysql-master ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 76
Server version: 8.0.41 Source distribution
​
Copyright (c) 2000, 2025, Oracle and/or its affiliates.
​
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
​
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
​
mysql> create user slave@'192.168.58.%' identified by '123.com';    #创建从主机可以进行访问的用户slave
Query OK, 0 rows affected (0.02 sec)
​
mysql> grant all on *.* to slave@'192.168.58.%';    #给slave用户赋权
Query OK, 0 rows affected (0.02 sec)
​
mysql> exit
Bye
[root@mysql-master ~]# vim /etc/my.cnf.d/mysql-server.cnf 
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
#添加命令,启用二进制日志记录功能
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
log-bin=mysql-bin
binlog_format="statement"
[root@mysql-master ~]# systemctl restart mysqld
#关闭防火墙和SELinux
[root@mysql-master ~]# systemctl stop firewalld
[root@mysql-master ~]# setenforce 0
[root@mysql-master ~]# cd /var/lib/mysql
#验证配置
[root@mysql-master mysql]# ls
 auto.cnf          db1                  mysql-bin.000001     private_key.pem
 binlog.000001    '#ib_16384_0.dblwr'   mysql-bin.index      public_key.pem
 binlog.000002    '#ib_16384_1.dblwr'   mysql.ibd            server-cert.pem
 binlog.000003     ib_buffer_pool       mysql.sock           server-key.pem
 binlog.index      ibdata1              mysql.sock.lock      sys
 ca-key.pem        ibtmp1               mysql_upgrade_info   test
 ca.pem           '#innodb_redo'        mysqlx.sock          test2
 client-cert.pem  '#innodb_temp'        mysqlx.sock.lock     undo_001
 client-key.pem    mysql                performance_schema   undo_002
​
[root@mysql-master mysql]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.41 Source distribution
​
Copyright (c) 2000, 2025, Oracle and/or its affiliates.
​
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
​
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
​
#查看master正在使用的日志文件及日志书写位置
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 |      157 |              |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
#注意:查看位置完毕后,不要对master做任何操作,等配置完从服务再进行其余操作

从服务器配置

对时

#192.168.58.161
[root@localhost ~]# timedatectl set-timezone Asia/Shanghai
[root@mysql ~]# vim /etc/chrony.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
pool 2.rocky.pool.ntp.org iburst
​
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
​
##添加修改此字段
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#pool 2.rocky.pool.ntp.org iburst
server ntp.aliyun.com iburst
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
​
[root@mysql ~]# systemctl restart chronyd.service 
[root@localhost ~]# hostnamectl set-hostname mysql-slave
[root@localhost ~]# bash
[root@mysql-slave ~]# vim /etc/my.cnf.d/mysql-server.cnf 
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
#添加命令,启用二进制日志中继日志
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid
binlog_format="statement"
relay-log-index=slave-bin.index
​
[root@mysql-slave ~]# systemctl restart mysqld
#关闭防火墙和SELinux
[root@mysql-slave ~]# systemctl stop firewalld
[root@mysql-slave ~]# setenforce 0
[root@mysql-slave ~]# cd /var/lib/mysql
#配置验证,此时没有与主服务器进行连接,所以没有产生对应的relay log
[root@mysql-slave mysql]# ls
 auto.cnf         '#ib_16384_0.dblwr'   mysql.ibd            public_key.pem
 binlog.000001    '#ib_16384_1.dblwr'   mysql.sock           server-cert.pem
 binlog.000002     ib_buffer_pool       mysql.sock.lock      server-key.pem
 binlog.index      ibdata1              mysql_upgrade_info   sys
 ca-key.pem        ibtmp1               mysqlx.sock          undo_001
 ca.pem           '#innodb_redo'        mysqlx.sock.lock     undo_002
 client-cert.pem  '#innodb_temp'        performance_schema
 client-key.pem    mysql                private_key.pem
[root@mysql-slave mysql]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 8.0.41 Source distribution
​
Copyright (c) 2000, 2025, Oracle and/or its affiliates.
​
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
​
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
​
##配置从服务器的所属主服务器
mysql> change master to master_host='192.168.58.160',master_user='slave',master_password='123.com',master_log_file='mysql-bin.000001',master_log_pos=157;
Query OK, 0 rows affected, 8 warnings (0.02 sec)
​
##启动slave角色,默认没有配置主从时,所有的mysql节点都是master
mysql> start slave;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
​
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.01 sec)

验证结果

#192.168.58.160
#创建新库c2505
mysql> create database c2505;
Query OK, 1 row affected (0.00 sec)
​
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| c2505              |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
8 rows in set (0.01 sec)
​
#192.168.58.161
#验证,查看到这里也创建了一个新库c2505
mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| c2505              |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)
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