主从复制使数据可以从一个数据库服务器复制到其他服务器上，在复制数据时，一个服务器充当主服务器（master），其余的服务器充当从服务器（slave）。
MySQL可以使用一组一从、一主多从等形式进行搭建服务器，本实例使用一主一从模式进行搭建。 使用本地PC环境的VMWare Workstation软件进，准备两台CentOS7.2虚拟机，虚拟机配置为1核/2G内存/20G硬盘。
1.配置IP地址，修改两个服务器的主机名。 主节点：
[root@localhost ~]# hostnamectl set-hostname master [root@localhost ~]# logout [root@master ~]# hostnamectl Static hostname: master Icon name: computer-vm Chassis: vm Machine ID: 179f6c8f2e7942ef81b0f5565a6883fa Boot ID: 69ad020d53e54892b9005f82e182c140 Virtualization: vmware Operating System: CentOS Linux 7 (Core) CPE OS Name: cpe:/o:centos:centos:7 Kernel: Linux 3.10.0-327.el7.x86_64 Architecture: x86-64从节点：
[root@localhost ~]# hostnamectl set-hostname slave [root@localhost ~]# logout [root@slave ~]# hostnamectl Static hostname: slave Icon name: computer-vm Chassis: vm Machine ID: 179f6c8f2e7942ef81b0f5565a6883fa Boot ID: 816b270a1275496caa3254300fc359c4 Virtualization: vmware Operating System: CentOS Linux 7 (Core) CPE OS Name: cpe:/o:centos:centos:7 Kernel: Linux 3.10.0-327.el7.x86_64 Architecture: x86-642.双节点关闭防火墙、selinux服务以及配置hosts文件。 关闭防火墙selinux服务：
# setenforce 0 # systemctl stop firewalld配置hosts文件：
# cat /etc/hosts 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 10.10.10.1 master 10.10.10.2 slave3.双节点安装数据库服务。 首先配置yum源，我这里是使用本地的yum源，供参考：
# mv /etc/yum.repos.d/C* /media //移动yum源，防止与配置的yum源出现冲突 # mount /dev/cdrom /mnt/ //挂载本地镜像到/mnt下 [root@localhost ~]# cat /etc/yum.repos.d/local.repo [centos] name=centos baseurl=file:///mnt/ gpgcheck=0 enabled=1 # yum clean all //清空所有源 Loaded plugins: fastestmirror Cleaning repos: centos Cleaning up everything Cleaning up list of fastest mirrors # yum repolist //查看拥有仓库源 Loaded plugins: fastestmirror centos | 3.6 kB 00:00:00 (1/2): centos/group_gz | 155 kB 00:00:00 (2/2): centos/primary_db | 2.8 MB 00:00:00 Determining fastest mirrors repo id repo name status centos centos 3,723 repolist: 3,723安装数据库：
# yum install -y mariadb mariadb-server开启数据库服务，并设置开机自启动：
# systemctl start mariadb # systemctl enable mariadb Created symlink from /etc/systemd/system/multi-user.target.wants/mariadb.service to /usr/lib/systemd/system/mariadb.service.1.双节点初始化数据库。
# mysql_secure_installation /usr/bin/mysql_secure_installation: line 379: find_mysql_client: command not found NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY! In order to log into MariaDB to secure it, we'll need the current password for the root user. If you've just installed MariaDB, and you haven't set the root password yet, the password will be blank, so you should just press enter here. Enter current password for root (enter for none): #默认按回车 OK, successfully used password, moving on... Setting the root password ensures that nobody can log into the MariaDB root user without the proper authorisation. Set root password? [Y/n] y New password: #输入数据库root密码000000 Re-enter new password: #再次输入密码000000 Password updated successfully! Reloading privilege tables.. ... Success! By default, a MariaDB installation has an anonymous user, allowing anyone to log into MariaDB without having to have a user account created for them. This is intended only for testing, and to make the installation go a bit smoother. You should remove them before moving into a production environment. Remove anonymous users? [Y/n] y ... Success! Normally, root should only be allowed to connect from 'localhost'. This ensures that someone cannot guess at the root password from the network. Disallow root login remotely? [Y/n] n ... skipping. By default, MariaDB comes with a database named 'test' that anyone can access. This is also intended only for testing, and should be removed before moving into a production environment. Remove test database and access to it? [Y/n] y - Dropping test database... ... Success! - Removing privileges on test database... ... Success! Reloading the privilege tables will ensure that all changes made so far will take effect immediately. Reload privilege tables now? [Y/n] y ... Success! Cleaning up... All done! If you've completed all of the above steps, your MariaDB installation should now be secure. Thanks for using MariaDB!2.配置数据库文件。 master节点： 修改配置文件/etc/my.cnf中的[mysqld]增添如下内容：
[root@master ~]# cat /etc/my.cnf [mysqld] log_bin = mysql-bin #记录操作日志 binlog_ignore_db = mysql #不同步mysql系统数据库 server_id = 1 #数据库集群中的每个节点id都要不同，一般使用IP地址的最后段的数字，例如10.10.10.1，server_id就写1 datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 # 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重启数据库服务
[root@master ~]# systemctl restart mariadbslave节点：
[root@slave ~]# cat /etc/my.cnf [mysqld] log_bin = mysql-bin #记录操作日志 binlog_ignore_db = mysql #不同步mysql系统数据库 server_id = 2 #数据库集群中的每个节点id都要不同，一般使用IP地址的最后段的数字，例如10.10.10.2，server_id就写2 datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 # 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重启数据库服务：
[root@slave ~]# systemctl restart mariadb3.配置主从连接。 master节点: 进入数据库，授权在任何客户端机器上可以以root用户登录到数据库，然后在主节点上创建一个user用户连接节点slave，并赋予从节点同步主节点数据库的权限：
[root@master ~]# mysql -uroot -p000000 Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 2 Server version: 5.5.44-MariaDB-log MariaDB Server Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> MariaDB [(none)]> grant all privileges on *.* to root@'%' identified by "000000"; Query OK, 0 rows affected (0.00 sec) MariaDB [(none)]> grant replication slave on *.* to 'user'@'slave' identified by '000000'; Query OK, 0 rows affected (0.00 sec)slave节点： 进入数据库，配置从节点连接主节点的连接信息。master_host为主节点主机名master，master_user为上一步中创建的用户user：
[root@slave ~]# mysql -uroot -p000000 Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 10 Server version: 5.5.44-MariaDB MariaDB Server Copyright (c) 2000, 2015, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]> change master to master_host='master',master_user='user',master_password='000000'; Query OK, 0 rows affected (0.01 sec)4.查看服务状态 slave节点开启从节点服务，查看从节点服务状态：
MariaDB [(none)]> start slave; MariaDB [(none)]> show slave status\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: mysql1 Master_User: user Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-bin.000003 Read_Master_Log_Pos: 245 Relay_Log_File: mariadb-relay-bin.000005 Relay_Log_Pos: 529 Relay_Master_Log_File: mysql-bin.000003 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: 245 Relay_Log_Space: 1256 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: 30 1 row in set (0.00 sec)可以看到Slave_IO_Running和Slave_SQL_Running的状态都是Yes，配置数据库主从集群成功。
