目录
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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