MYSQL主主复制：互为主从

容易产生的问题：数据不一致

主机	IP
Master1	192.168.37.7
Master2	192.168.37.17

Master1设置

[root@Centos7 ~]#vim /etc/my.cnf
[mysqld]
log_bin
server_id=7
auto_increment_offset=1
auto_increment_increment=2

创建复制帐号

MariaDB [(none)]> grant replication slave on *.* to repluser@'192.168.37.%' identified by 'centos';

Master2设置

[root@Centos7 ~]#vim /etc/my.cnf
[mysqld]
log_bin
server_id=17
auto_increment_offset=2
auto_increment_increment=2

同步信息master2同步master1

MariaDB [(none)]> CHANGE MASTER TO   
    -> MASTER_HOST='192.168.37.7',
    -> MASTER_USER='repluser',
    -> MASTER_PASSWORD='centos',
    -> MASTER_PORT=3306,
    -> MASTER_LOG_FILE='mariadb-bin.000001', 
    -> MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.03 sec)
MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.01 sec)

Master1同步Master2

MariaDB [(none)]> CHANGE MASTER TO   
    -> MASTER_HOST='192.168.37.17',
    -> MASTER_USER='repluser',
    -> MASTER_PASSWORD='centos',
    -> MASTER_PORT=3306,
    -> MASTER_LOG_FILE='mariadb-bin.000001', 
    -> MASTER_LOG_POS=245;
Query OK, 0 rows affected (0.03 sec)
MariaDB [(none)]> START SLAVE;
Query OK, 0 rows affected (0.01 sec)

主主复制完成

半同步复制

半同步是当若干从服务器中有一台与主服务器同步成功，就认为同步成功。返回结果给客户机
半同步需要安装独立的插件来实现
查看已安装插件show plugins;
semisync_master.so 主服务器插件
semisync_slave.so 从服务器插件
条件：设置为主从复制

Master

MariaDB [(none)]> INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';  #安装插件
Query OK, 0 rows affected (0.01 sec)

开启master半同步复制

[root@Centos7 ~]#vim /etc/my.cnf
rpl_semi_sync_master_enabled                 #添加服务器选项 
[root@Centos7 ~]#systemctl restart mariadb   #重启服务生效

slave

MariaDB [hellodb]> INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';   #安装插件
Query OK, 0 rows affected (0.02 sec)

###- 开启slave半同步复制

[root@Centos7 ~]#vim /etc/my.cnf
rpl_semi_sync_slave_enabled                  #添加服务器选项
[root@Centos7 ~]#systemctl restart mariadb   #重启服务生效

半同步设置完成

MariaDB [(none)]> show global status like '%semi%';  #查看复制信息
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 1     |
| Rpl_semi_sync_master_net_avg_wait_time     | 0     |
| Rpl_semi_sync_master_net_wait_time         | 0     |
| Rpl_semi_sync_master_net_waits             | 0     |
| Rpl_semi_sync_master_no_times              | 0     |
| Rpl_semi_sync_master_no_tx                 | 0     |
| Rpl_semi_sync_master_status                | ON    |
| Rpl_semi_sync_master_timefunc_failures     | 0     |
| Rpl_semi_sync_master_tx_avg_wait_time      | 0     |
| Rpl_semi_sync_master_tx_wait_time          | 0     |
| Rpl_semi_sync_master_tx_waits              | 0     |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     |
| Rpl_semi_sync_master_wait_sessions         | 0     |
| Rpl_semi_sync_master_yes_tx                | 0     |
+--------------------------------------------+-------+
14 rows in set (0.44 sec)

MariaDB [(none)]> show global variables like '%semi%';
+------------------------------------+-------+
| Variable_name                      | Value |
+------------------------------------+-------+
| rpl_semi_sync_master_enabled       | ON    |  #已开启半同步
| rpl_semi_sync_master_timeout       | 10000 |  #超时时长10000ms  
| rpl_semi_sync_master_trace_level   | 32    |
| rpl_semi_sync_master_wait_no_slave | ON    |
+------------------------------------+-------+
4 rows in set (0.00 sec)

MariaDB [(none)]>

MariaDB [(none)]> show global status like '%semi%';
+----------------------------+-------+
| Variable_name              | Value |
+----------------------------+-------+
| Rpl_semi_sync_slave_status | ON    |
+----------------------------+-------+
1 row in set (0.02 sec)

MariaDB [(none)]> show global variables like '%semi%';
+---------------------------------+-------+
| Variable_name                   | Value |
+---------------------------------+-------+
| rpl_semi_sync_slave_enabled     | ON    |
| rpl_semi_sync_slave_trace_level | 32    |
+---------------------------------+-------+
2 rows in set (0.01 sec)

主主复制，半同步复制