主从介绍

Mysql主从又叫Replication、AB复制。简单讲就是A与B两台机器做主从后，在A上写数据，另外一台B也会跟着写数据，实现数据实时同步

mysql主从是基于binlog，主上需开启binlog才能进行主从

主从过程大概有3个步骤

主将更改操作记录到binlog里

从将主的binlog事件（sql语句） 同步本机上并记录在relaylog里

从根据relaylog里面的sql语句按顺序执行

主从作用

• 实时灾备，用于故障切换
• 读写分离，提供查询服务
• 备份，避免影响业务

主从形式

* 一主一从* 主主复制* 一主多从---扩展系统读取的性能，因为读是在从库读取的* 多主一从---5.7版本开始支持* 联级复制

主从复制原理

主从复制步骤

• 主库将所有的写操作记录在binlog日志中，并生成log dump线程，将binlog日志传给从库的I/O线程

• 从库生成两个线程，一个是I/O线程，另一个是SQL线程

• I/O线程去请求主库的binlog日志，并将binlog日志中的文件写入relay log（中继日志）中
• SQL线程会读取relay loy中的内容，并解析成具体的操作，来实现主从的操作一致，达到最终数据一致的目的

主从复制配置步骤：

1. 确保从数据库与主数据库里的数据一致
2. 在主数据库里创建一个同步账户授权给从数据库使用
3. 配合主数据库（修改配置文件）
4. 配置从数据库（修改配置文件）

需求

搭建两台MYSQL服务器，一台作为主服务器，一台作为从服务器，主服务器进行写操作，从服务器进行读操作

环境说明

数据库角色	IP	应用与系统	有无数据
主数据库	192.168.55.130	centos7 mysql-5.7	有
从数据库	192.168.55.129	centos7 mysql-5.7	无

在两台服务器上都按装mysql

环境准备关闭防火墙以SELINUX[root@yanyinglai ~]# systemctl stop firewalld[root@yanyinglai ~]# systemctl disable firewalld[root@yanyinglai ~]#  sed -ri 's/(SELINUX=).*/\1disabled/g' /etc/selinux/config[root@yanyinglai ~]# setenforce 0安装mysql安装依赖包[root@yanyinglai ~]# yum -y install ncurses-devel openssl-devel openssl cmake mariadb-devel创建用户和组[root@yanyinglai ~]# groupadd -r -g 306 mysql[root@yanyinglai ~]# useradd -M -s /sbin/nologin -g 306 -u 306 mysql下载二进制格式的mysql软件包[root@yanyinglai ~]# cd /usr/src/[root@yanyinglai src]#wget https://downloads.mysql.com/archives/get/file/mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz解压软件至/usr/local/[root@yanyinglai src]# lsdebug  kernels  mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz[root@yanyinglai src]# tar xf mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz -C /usr/local/[root@yanyinglai src]#  ls  /usr/local/bin  etc  games  include  lib  lib64  libexec  mysql-5.7.22-linux-glibc2.12-x86_64  sbin  share  src[root@yanyinglai src]#  cd  /usr/local/[root@yanyinglai local]# ln -sv mysql-5.7.22-linux-glibc2.12-x86_64/ mysql"mysql" -> "mysql-5.7.22-linux-glibc2.12-x86_64/"[root@yanyinglai local]# ll总用量 0drwxr-xr-x. 2 root root   6 11月  5 2016 bindrwxr-xr-x. 2 root root   6 11月  5 2016 etcdrwxr-xr-x. 2 root root   6 11月  5 2016 gamesdrwxr-xr-x. 2 root root   6 11月  5 2016 includedrwxr-xr-x. 2 root root   6 11月  5 2016 libdrwxr-xr-x. 2 root root   6 11月  5 2016 lib64drwxr-xr-x. 2 root root   6 11月  5 2016 libexeclrwxrwxrwx. 1 root root  36 9月   7 22:20 mysql -> mysql-5.7.22-linux-glibc2.12-x86_64/drwxr-xr-x. 9 root root 129 9月   7 22:19 mysql-5.7.22-linux-glibc2.12-x86_64drwxr-xr-x. 2 root root   6 11月  5 2016 sbindrwxr-xr-x. 5 root root  49 9月   3 23:02 sharedrwxr-xr-x. 2 root root   6 11月  5 2016 src修改目录/usr/locaal/mysql的属主属组[root@yanyinglai local]# chown -R mysql.mysql /usr/local/mysql[root@yanyinglai local]#  ll /usr/local/mysql -dlrwxrwxrwx. 1 mysql mysql 36 9月   7 22:20 /usr/local/mysql -> mysql-5.7.22-linux-glibc2.12-x86_64/添加环境变量[root@yanyinglai local]# ls /usr/local/mysqlbin  COPYING  docs  include  lib  man  README  share  support-files[root@yanyinglai local]# cd[root@yanyinglai ~]# echo 'export PATH=/usr/local/mysql/bin:$PATH' > /etc/profile.d/mysql.sh[root@yanyinglai ~]# . /etc/profile.d/mysql.sh[root@yanyinglai ~]# echo $PATH/usr/local/mysql/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin建立数据存放目录[root@yanyinglai ~]# cd /usr/local/mysql[root@yanyinglai mysql]# mkdir /opt/data[root@yanyinglai mysql]#  chown -R mysql.mysql /opt/data/[root@yanyinglai mysql]#  ll /opt/总用量 0drwxr-xr-x. 2 mysql mysql 6 9月   7 22:25 data初始化数据库[root@yanyinglai mysql]# /usr/local/mysql/bin/mysqld --initialize --user=mysql --datadir=/opt/data///这个命令的最后会生成一个临时密码，此处密码是1EbNA-k*BtKo配置mysql[root@yanyinglai ~]# ln -sv /usr/local/mysql/include/ /usr/local/include/mysql"/usr/local/include/mysql" -> "/usr/local/mysql/include/"[root@yanyinglai ~]# echo '/usr/local/mysql/lib' > /etc/ld.so.conf.d/mysql.conf[root@yanyinglai ~]#  ldconfig -v生成配置文件[root@yanyinglai ~]# cat > /etc/my.cnf <
    
      [mysqld]> basedir = /usr/local/mysql> datadir = /opt/data> socket = /tmp/mysql.sock> port = 3306> pid-file = /opt/data/mysql.pid> user = mysql> skip-name-resolve> EOF配置服务启动脚本[root@yanyinglai ~]# cp -a /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld[root@yanyinglai ~]#  sed -ri 's#^(basedir=).*#\1/usr/local/mysql#g' /etc/init.d/mysqld[root@yanyinglai ~]# sed -ri 's#^(datadir=).*#\1/opt/data#g' /etc/init.d/mysqld启动mysql[root@yanyinglai ~]#  service mysqld startStarting MySQL.Logging to '/opt/data/yanyinglai.err'... SUCCESS![root@yanyinglai ~]#  ps -ef|grep mysqlroot       4897      1  0 22:38 pts/2    00:00:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/opt/data --pid-file=/opt/data/mysql.pidmysql      5075   4897  6 22:38 pts/2    00:00:01 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/opt/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=yanyinglai.err --pid-file=/opt/data/mysql.pid --socket=/tmp/mysql.sock --port=3306root       5109   4668  0 22:38 pts/2    00:00:00 grep --color=auto mysql[root@yanyinglai ~]# ss -antlState       Recv-Q Send-Q                     Local Address:Port                                    Peer Address:Port              LISTEN      0      128                                    *:22                                                 *:*                  LISTEN      0      100                            127.0.0.1:25                                                 *:*                  LISTEN      0      128                                   :::22                                                :::*                  LISTEN      0      100                                  ::1:25                                                :::*                  LISTEN      0      80                                    :::3306                                              :::*                  修改密码使用临时密码修改[root@yanyinglai ~]# mysql -uroot -pEnter password:Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 2Server version: 5.7.22Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> set password = password('123456');Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> quitByemysql主从配置确保从数据库与主数据库的数据一样先在主数据库创建所需要同步的库和表[root@yanyinglai ~]# mysql -uroot -pEnter password:Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 4Server version: 5.7.22 MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle and/or its affiliates. AlOracle is a registered trademark of Oracle Corporation andaffiliates. Other names may be trademarks of their respectowners.Type 'help;' or '\h' for help. Type '\c' to clear the currmysql> create database yan;Query OK, 1 row affected (0.00 sec)mysql> create database lisi;Query OK, 1 row affected (0.00 sec)mysql> create database wangwu;Query OK, 1 row affected (0.00 sec)mysql> use yan;Database changedmysql> create table tom (id int not null,name varchar(100)not null ,age tinyint);Query OK, 0 rows affected (11.83 sec)mysql> insert tom (id,name,age) values(1,'zhangshan',20),(2,'wangwu',7),(3,'lisi',23);Query OK, 3 rows affected (0.07 sec)Records: 3  Duplicates: 0  Warnings: 0mysql> select * from tom;+----+-----------+------+| id | name      | age  |+----+-----------+------+|  1 | zhangshan |   20 ||  2 | wangwu    |    7 ||  3 | lisi      |   23 |+----+-----------+------+3 rows in set (0.00 sec)备份主库备份主库时需要另开一个终端，给数据库上读锁，避免在备份期间有其他人在写入导致数据同步的不一致[root@yanyinglai ~]# mysql -uroot -pEnter password:Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 5Server version: 5.7.22 MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> flush tables with read lock;Query OK, 0 rows affected (0.76 sec)//此锁表的终端必须在备份完成以后才能退出（退出锁表失效）备份主库并将备份文件传送到从库[root@yanyinglai ~]# mysqldump -uroot -p123456 --all-databases > /opt/all-20180907.sqlmysqldump: [Warning] Using a password on the command line interface can be insecure.[root@yanyinglai ~]# ls /opt/all-20180907.sql  data[root@yanyinglai ~]# scp /opt/all-20180907.sql root@192.168.55.129:/opt/The authenticity of host '192.168.55.129 (192.168.55.129)' can't be established.ECDSA key fingerprint is SHA256:7mLj77SFk7sPkhjpMPfdK3nZ98hOuyP4OKzjXeijSJ0.ECDSA key fingerprint is MD5:a0:1b:eb:7f:f0:b6:7b:73:97:91:4c:f3:b1:89:d8:ea.Are you sure you want to continue connecting (yes/no)? yesWarning: Permanently added '192.168.55.129' (ECDSA) to the list of known hosts.root@192.168.55.129's password:all-20180907.sql       100%  784KB 783.3KB/s   00:01    解除主库的锁表状态，直接退出交互式界面即可mysql> quitBye在从库上恢复主库的备份并查看是否与主库的数据保持一致[root@yanyinglai ~]# mysql -uroot -p123456 < /opt/all-20180907.sqlmysql: [Warning] Using a password on the command line interface can be insecure.[root@yanyinglai ~]# mysql -uroot -p123456mysql: [Warning] Using a password on the command line interface can be insecure.Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 4Server version: 5.7.22 MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> show databases;+--------------------+| Database           |+--------------------+| information_schema || lisi               || mysql              || performance_schema || sys                || wangwu             || yan                |+--------------------+7 rows in set (0.18 sec)mysql> use yan;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> select * from tom;+----+-----------+------+| id | name      | age  |+----+-----------+------+|  1 | zhangshan |   20 ||  2 | wangwu    |    7 ||  3 | lisi      |   23 |+----+-----------+------+3 rows in set (0.06 sec)在主数据库创建一个同步账户授权给从数据使用[root@yanyinglai ~]# mysql -uroot -pEnter password:Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 7Server version: 5.7.22 MySQL Community Server (GPL)Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> create user 'repl'@'192.168.55.129' identified by '123456';Query OK, 0 rows affected (5.50 sec)mysql> grant replication slave on *.* to 'repl'@'192.168.55.129';Query OK, 0 rows affected (0.04 sec)mysql> flush privileges;Query OK, 0 rows affected (0.09 sec)配置主数据库编辑配置文件[root@yanyinglai ~]# vim /etc/my.cnf[root@yanyinglai ~]# cat /etc/my.cnf[mysqld]basedir = /usr/local/mysqldatadir = /opt/datasocket = /tmp/mysql.sockport = 3306pid-file = /opt/data/mysql.piduser = mysqlskip-name-resolve//添加以下内容log-bin=mysql-bin //启用binlog日志server-id=1 //主数据库服务器唯一标识符 主的必须必从大log-error=/opt/data/mysql.log重启mysql服务[root@yanyinglai ~]# service mysqld restartShutting down MySQL..... SUCCESS!Starting MySQL.Logging to '/opt/data/mysql.log'................................ SUCCESS![root@yanyinglai ~]# ss -antlState       Recv-Q Send-Q Local Address:Port               Peer Address:Port              LISTEN      0      128     *:22                  *:*                  LISTEN      0      100    127.0.0.1:25                  *:*                  LISTEN      0      128    :::22                 :::*                  LISTEN      0      100       ::1:25                 :::*                  LISTEN      0      80     :::3306               :::*查看主库的状态mysql> show master status;+------------------+----------+--------------+------------------+-------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |+------------------+----------+--------------+------------------+-------------------+| mysql-bin.000001 |      154 |              |                  |                   |+------------------+----------+--------------+------------------+-------------------+1 row in set (0.00 sec)配置从数据库编辑配置文件[root@yanyinglai ~]# cat /etc/my.cnf[mysqld]basedir = /usr/local/mysqldatadir = /opt/datasocket = /tmp/mysql.sockport = 3306pid-file = /opt/data/mysql.piduser = mysqlskip-name-resolve//添加以下内容：server-id=2 //设置从库的唯一标识符 从的必须比主小relay-log=mysql-relay-bin //启用中继日志relay logerror-log=/opt/data/mysql.log重启从库的mysql服务[root@yanyinglai ~]# service mysqld restartShutting down MySQL.. SUCCESS!Starting MySQL.. SUCCESS![root@yanyinglai ~]# ss -antlState       Recv-Q Send-Q Local Address:Port               Peer Address:Port              LISTEN      0      128     *:22                  *:*                  LISTEN      0      100    127.0.0.1:25                  *:*                  LISTEN      0      128    :::22                 :::*                  LISTEN      0      100       ::1:25                 :::*                  LISTEN      0      80     :::3306               :::*                  配置并启动主从复制mysql> change master to    -> master_host='192.168.55.130',    -> master_user='repl',    -> master_password='123456',    -> master_log_file='mysql-bin.000001',    -> master_log_pos=154;Query OK, 0 rows affected, 2 warnings (0.28 sec)查看从服务器状态mysql> show slave status\G;*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.55.130                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 154               Relay_Log_File: mysql-relay-bin.000003                Relay_Log_Pos: 320        Relay_Master_Log_File: mysql-bin.000001             Slave_IO_Running: Yes                                     //此处必须是yes            Slave_SQL_Running: Yes                                    //此处必须是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: 154              Relay_Log_Space: 527              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: 0Master_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                  Master_UUID: 5abf1791-b2af-11e8-b6ad-000c2980fbb4             Master_Info_File: /opt/data/master.info                    SQL_Delay: 0          SQL_Remaining_Delay: NULL      Slave_SQL_Running_State: Slave 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:1 row in set (0.00 sec)ERROR:No query specified测试验证在主服务器的yan库的tom表插入数据:mysql> use yan;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> select * from tom;+----+-----------+------+| id | name      | age  |+----+-----------+------+|  1 | zhangshan |   20 ||  2 | wangwu    |    7 ||  3 | lisi      |   23 |+----+-----------+------+3 rows in set (0.09 sec)mysql> insert tom(id,name,age) value (4,"yyl",18);Query OK, 1 row affected (0.14 sec)mysql> select * from tom;+----+-----------+------+| id | name      | age  |+----+-----------+------+|  1 | zhangshan |   20 ||  2 | wangwu    |    7 ||  3 | lisi      |   23 ||  4 | yyl       |   18 |+----+-----------+------+4 rows in set (0.00 sec)在从数据库查看是否数据同步mysql> use yan;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> select * from tom;+----+-----------+------+| id | name      | age  |+----+-----------+------+|  1 | zhangshan |   20 ||  2 | wangwu    |    7 ||  3 | lisi      |   23 ||  4 | yyl       |   18 |+----+-----------+------+4 rows in set (0.00 sec)