mysql主从复制

1、介绍

       MySQL作为世界上使用最为广泛的数据库之一，免费是其原因之一。但不可忽略的是它本身的功能的确很强大。随着技术的发展，在实际的生产环境中，由单台MySQL数据库服务器不能满足实际的需求。此时数据库集群就很好的解决了这个问题了。采用MySQL分布式集群，能够搭建一个高并发、负载均衡的集群服务器（这篇博客暂时不涉及）。在此之前我们必须要保证每台MySQL服务器里的数据同步。数据同步我们可以通过MySQL内部配置就可以轻松完成，主要有主从复制和主主复制。

2、环境

主：192.168.182.155 centos7.2   

从：192.168.182.156 centos7.2   

3、主从复制

3.1、修改配置文件

修改主从服务器的配置文件/etc/my.cnf，在mysqld中添加log-bin=mysql-bin开启二进制文件

主服务配置：

[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
#
[client-server]

#
# This group is read by the server
#
[mysqld]
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-bin=mysql-bin

  server-id=1
  innodb_flush_log_at_trx_commit=1
  sync_binlog=1
  binlog_ignore_db=mysql

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

从服务器配置：

[root@localhost ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-bin=mysql-bin

server-id=2

# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid


#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

 3.2、开始构建主从复制

在192.168.182.155中创建一个192.168.182.156主机中可以登录的MySQL用户

登陆主数据库

mysql  -uroot -pwc20080512;

创建连接账号和密码

MariaDB [(none)]> CREATE USER 'mysql12'@ '192.168.182.156' IDENTIFIED BY 'mysql12';

授权

MariaDB [(none)]> GRANT REPLICATION SLAVE ON *.* TO 'mysql12'@192.168.182.156 IDENTIFIED BY 'mysql12';
Query OK, 0 rows affected (0.02 sec)

  MariaDB [(none)]> FLUSH PRIVILEGES;
  Query OK, 0 rows affected (0.02 sec)

执行以下命令锁定数据库以防止写入数据

MariaDB [(none)]> FLUSH TABLES WITH READ LOCK;
Query OK, 0 rows affected (0.07 sec)

退出mysql命令行，导出数据库

mysqldump  -uroot -pwc20080512  -B heruiguo  wanghaixue > /opt/mysql.sql;

scp 数据文件到从服务器

 scp /opt/mysql.sql  192.168.182.156:/opt

登陆从服务器导入数据

[root@localhost ~]# mysql -uroot -pwc20080512</opt/mysql.sql 

编辑配置文件my.cnf,在[mysqld]下面加入：

server-id=2

重启数据库

systemctl  restart  mariadb.service

查看192.168.182.155 MySQL服务器二进制文件名与位置

MariaDB [(none)]> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000010 | 327 | wordpress | mysql |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

解锁数据库

MariaDB [(none)]> UNLOCK TABLES;
Query OK, 0 rows affected (0.00 sec)

在从服务器执行

[root@localhost ~]# mysql   -uroot  -pwc20080512

CHANGE MASTER TO
MASTER_HOST='192.168.182.155',
MASTER_USER='mysql12',
MASTER_PASSWORD='mysql12',
MASTER_PORT=3306,
MASTER_LOG_FILE='mysql-bin.000010',
MASTER_LOG_POS=327;

启动slave进程。

MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected, 1 warning (0.00 sec)

查看主从复制是否配置成功

MariaDB [(none)]> SHOW SLAVE STATUSG  
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.182.155
                  Master_User: mysql12
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000010
          Read_Master_Log_Pos: 723
               Relay_Log_File: mariadb-relay-bin.000002
                Relay_Log_Pos: 929
        Relay_Master_Log_File: mysql-bin.000010
             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: 723
              Relay_Log_Space: 1225
              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: 1
1 row in set (0.00 sec)

主从配置完成

测试

在主服务器上创建数据库

MariaDB [heruiguo]> create  database  aaa;
Query OK, 1 row affected (0.01 sec)

MariaDB [heruiguo]> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000012 |      624 |              | mysql            |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

在从库上验证

MariaDB [heruiguo]> show  databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| aaa                |
| heruiguo           |
| mysql              |
| performance_schema |
| wanghaixue         |
+--------------------+
6 rows in set (0.00 sec)