MySQL5.7多主一从（多源复制）同步配置

多主一从，也称为多源复制，数据流向：

• 主库1 -> 从库s
• 主库2 -> 从库s
• 主库n -> 从库s

应用场景

• 数据汇总，可将多个主数据库同步汇总到一个从数据库中，方便数据统计分析。
• 读写分离，从库只用于查询，提高数据库整体性能。

部署环境

​ 注：使用docker部署mysql实例，方便快速搭建演示环境。但本文重点是讲解主从配置，因此简略描述docker环境构建mysql容器实例。

• 数据库：MySQL 5.7.x （相比5.5，5.6而言，5.7同步性能更好，支持多源复制，可实现多主一从，主从库版本应保证一致）
• 操作系统：CentOS 7.x
• 容器：Docker 17.09.0-ce
• 镜像：mysql:5.7
• 主库300：IP=192.168.10.212; PORT=4300; server-id=300; database=test3; table=user
• 主库400：IP=192.168.10.212; PORT=4400; server-id=400; database=test4; table=user
• 主库500：IP=192.168.10.212; PORT=4500; server-id=500; database=test5; table=user
• 从库10345：IP=192.168.10.212; PORT=4345; server-id=10345; database=test3,test4,test5; table=user

配置约束

• 主从库必须保证网络畅通可访问
• 主库必须开启binlog日志
• 主从库的server-id必须不同

事前准备

1. 关闭selinux

setenforce 0
vim /etc/sysconfig/selinux 
SELINUX=disabled

# 若不关闭，使用docker启动mysql5.7镜像容器时启动不起来，查看日志会有如下错误显示：
ERROR: mysqld failed while attempting to check config
command was: "mysqld --verbose --help"
mysqld: Can't read dir of '/etc/mysql/conf.d/' (Errcode: 13 - Permission denied)
mysqld: [ERROR] Fatal error in defaults handling. Program aborted!
ERROR: mysqld failed while attempting to check config
command was: "mysqld --verbose --help"
mysqld: Can't read dir of '/etc/mysql/conf.d/' (Errcode: 13 - Permission denied)
mysqld: [ERROR] Fatal error in defaults handling. Program aborted!

2. 安装并启动docker

yum install epel-release
yum -y install docker
systemctl start docker.service

3. 创建目录

mkdir -p /datavol/mysql-300/{mysql,conf}
mkdir -p /datavol/mysql-400/{mysql,conf}
mkdir -p /datavol/mysql-500/{mysql,conf}
mkdir -p /datavol/mysql-10345/{mysql,conf}

【主库300】操作及配置

配置my.cnf

把该文件放到主库所在配置文件路径下：/datavol/mysql-300/conf

[client]
port = 3306
default-character-set = utf8mb4

[mysql]
port = 3306
default-character-set = utf8mb4

[mysqld]
##########################
# summary
##########################
#bind-address = 0.0.0.0
#port = 3306
#datadir=/datavol/mysql/data #数据存储目录

##########################
# log bin
##########################
server-id = 300			#必须唯一
log_bin = mysql-bin 	#开启及设置二进制日志文件名称
binlog_format = MIXED
sync_binlog = 1
expire_logs_days =7		#二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。

#binlog_cache_size = 128m
#max_binlog_cache_size = 512m
#max_binlog_size = 256M

binlog-do-db = test3 	#要同步的数据库

binlog-ignore-db = mysql 	#不需要同步的数据库 
binlog_ignore_db = information_schema
binlog_ignore_db = performation_schema
binlog_ignore_db = sys
			

##########################
# character set
##########################
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4300:3306 --name=mysql-300 -v /datavol/mysql-300/conf:/etc/mysql/conf.d -v /datavol/mysql-300/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7
5691bac538e646db00273e3cad5b350dbe6cce0bd176346b7eefd9a6f9e3a9ad
[root@localhost ~]# docker ps
CONTAINER ID        IMAGE                               COMMAND                  CREATED             STATUS              PORTS                                                NAMES
5691bac538e6        mysql:5.7                           "docker-entrypoint..."   44 seconds ago      Up 43 seconds       33060/tcp, 0.0.0.0:4300->3306/tcp                    mysql-300
[root@localhost ~]# docker exec -it mysql-300 /bin/bash
root@5691bac538e6:/# mysql -u root -p
Enter password: 

注：若不熟悉docker，可使用传统方式安装mysql，效果相同。

创建授权用户

连接mysql主数据库，键入命令mysql -u root -p，输入密码后登录数据库。创建用户用于从库同步复制，授予复制、同步访问的权限

mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)

mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)

log_bin是否开启

mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | ON    |
+---------------+-------+
1 row in set

查看master状态

mysql> show master status G
*************************** 1. row ***************************
             File: mysql-bin.000003
         Position: 438
     Binlog_Do_DB: test3
 Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys

【主库400】配置及操作

配置my.cnf

把该文件放到主库所在配置文件路径下：/datavol/mysql-400/conf

[client]
port = 3306
default-character-set = utf8mb4

[mysql]
port = 3306
default-character-set = utf8mb4

[mysqld]
##########################
# summary
##########################
#bind-address = 0.0.0.0
#port = 3306
#datadir=/datavol/mysql/data #数据存储目录

##########################
# log bin
##########################
server-id = 400			#必须唯一
log_bin = mysql-bin 	#开启及设置二进制日志文件名称
binlog_format = MIXED
sync_binlog = 1
expire_logs_days =7		#二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。

#binlog_cache_size = 128m
#max_binlog_cache_size = 512m
#max_binlog_size = 256M

binlog-do-db = test4 		#要同步的数据库

binlog-ignore-db = mysql 	#不需要同步的数据库 
binlog_ignore_db = information_schema
binlog_ignore_db = performation_schema
binlog_ignore_db = sys
			

##########################
# character set
##########################
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4400:3306 --name=mysql-400 -v /datavol/mysql-400/conf:/etc/mysql/conf.d -v /datavol/mysql-400/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7
19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7
[root@localhost ~]# docker ps
CONTAINER ID        IMAGE                               COMMAND                  CREATED             STATUS              PORTS                                                NAMES
19e93b6d93ca        mysql:5.7                           "docker-entrypoint..."   4 seconds ago       Up 3 seconds        33060/tcp, 0.0.0.0:4400->3306/tcp                    mysql-400
[root@localhost ~]# docker exec -it mysql-400 /bin/bash
root@19e93b6d93ca:/# mysql -u root -p
Enter password: 

创建授权用户

创建用户用于从库同步复制，授予复制、同步访问的权限

mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)

mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)

log_bin是否开启

mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | ON    |
+---------------+-------+
1 row in set

查看master状态

mysql> show master status G;
*************************** 1. row ***************************
             File: mysql-bin.000003
         Position: 438
     Binlog_Do_DB: test4
 Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys

【主库500】配置及操作

配置my.cnf

把该文件放到主库所在配置文件路径下：/datavol/mysql-500/conf

[client]
port = 3306
default-character-set = utf8mb4

[mysql]
port = 3306
default-character-set = utf8mb4

[mysqld]
##########################
# summary
##########################
#bind-address = 0.0.0.0
#port = 3306
#datadir=/datavol/mysql/data #数据存储目录

##########################
# log bin
##########################
server-id = 500			#必须唯一
log_bin = mysql-bin 	#开启及设置二进制日志文件名称
binlog_format = MIXED
sync_binlog = 1
expire_logs_days =7		#二进制日志自动删除/过期的天数。默认值为0，表示不自动删除。

#binlog_cache_size = 128m
#max_binlog_cache_size = 512m
#max_binlog_size = 256M

binlog-do-db = test5 		#要同步的数据库

binlog-ignore-db = mysql 	#不需要同步的数据库 
binlog_ignore_db = information_schema
binlog_ignore_db = performation_schema
binlog_ignore_db = sys
			

##########################
# character set
##########################
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4500:3306 --name=mysql-500 -v /datavol/mysql-500/conf:/etc/mysql/conf.d -v /datavol/mysql-500/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7
19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7
[root@localhost ~]# docker ps
CONTAINER ID        IMAGE                               COMMAND                  CREATED             STATUS              PORTS                                                NAMES
19e93b6d93ca        mysql:5.7                           "docker-entrypoint..."   4 seconds ago       Up 3 seconds        33060/tcp, 0.0.0.0:4500->3306/tcp                    mysql-500
[root@localhost ~]# docker exec -it mysql-500 /bin/bash
root@19e93b6d93ca:/# mysql -u root -p
Enter password: 

创建授权用户

创建用户用于从库同步复制，授予复制、同步访问的权限

mysql> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)

mysql> grant replication slave on *.* to 'slave'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)

log_bin是否开启

mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | ON    |
+---------------+-------+
1 row in set

查看master状态

mysql> show master status G
*************************** 1. row ***************************
             File: mysql-bin.000003
         Position: 438
     Binlog_Do_DB: test5
 Binlog_Ignore_DB: mysql,information_schema,performation_schema,sys

【从库10345】配置及操作

配置my.cnf

把该文件放到主库所在配置文件路径下：/datavol/mysql-10345/conf

[client]
port = 3306
default-character-set = utf8mb4

[mysql]
port = 3306
default-character-set = utf8mb4

[mysqld]
##########################
# summary
##########################
#bind-address = 0.0.0.0
#port = 3306
#datadir=/datavol/mysql/data 	#数据存储目录

##########################
# log bin
##########################
server-id = 10345
master_info_repository      = table
relay_log_info_repository   = table		

##########################
# character set
##########################
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci

安装启动

[root@localhost ~]# docker run -d -p 4345:3306 --name=mysql-10345 -v /datavol/mysql-10345/conf:/etc/mysql/conf.d -v /datavol/mysql-10345/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7
19e93b6d93ca4e6ca0d540e3f6c831b835cdbb35362733867c3977aee4d33bf7
[root@localhost ~]# docker ps
CONTAINER ID        IMAGE                               COMMAND                  CREATED             STATUS              PORTS                                                NAMES
19e93b6d93ca        mysql:5.7                           "docker-entrypoint..."   4 seconds ago       Up 3 seconds        33060/tcp, 0.0.0.0:4345->3306/tcp                    mysql-10345
[root@localhost ~]# docker exec -it mysql-10345 /bin/bash
root@19e93b6d93ca:/# mysql -u root -p
Enter password: 

设置【主库】信息

登录【从库10345】，进入mysql命令行。

mysql> stop slave;
Query OK, 0 rows affected

mysql> CHANGE MASTER TO 
MASTER_HOST='192.168.10.212',
MASTER_PORT=4300,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=438 
for channel '300';
Query OK, 0 rows affected

mysql> CHANGE MASTER TO 
MASTER_HOST='192.168.10.212',
MASTER_PORT=4400,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=438 
for channel '400';
Query OK, 0 rows affected

mysql> CHANGE MASTER TO 
MASTER_HOST='192.168.10.212',
MASTER_PORT=4500,
MASTER_USER='slave',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=438 
for channel '500';
Query OK, 0 rows affected

mysql> start slave;
Query OK, 0 rows affected

stop slave; //停止同步
start slave; //开始同步
//必须和【主库】的信息匹配。
CHANGE MASTER TO
MASTER_HOST='192.168.10.212', //主库IP
MASTER_PORT=4300, //主库端口
MASTER_USER='slave', //访问主库且有同步复制权限的用户
MASTER_PASSWORD='123456', //登录密码
//【关键处】从主库的该log_bin文件开始读取同步信息，主库show master status返回结果
MASTER_LOG_FILE='mysql-bin.000003',
//【关键处】从文件中指定位置开始读取，主库show master status返回结果
MASTER_LOG_POS=438
**for channel '300'; //定义通道名称 **

查看同步状态

mysql> show slave status G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.10.212
                  Master_User: slave
                  Master_Port: 4300
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 1860
               Relay_Log_File: 0ad84f013600-relay-bin-300.000002
                Relay_Log_Pos: 1742
        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: 1860
              Relay_Log_Space: 1960
              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: 300
                  Master_UUID: 4efae154-ebd4-11e8-bf7d-0242ac110007
             Master_Info_File: mysql.slave_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: 300
           Master_TLS_Version: 
*************************** 2. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.10.212
                  Master_User: slave
                  Master_Port: 4400
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 2461
               Relay_Log_File: 0ad84f013600-relay-bin-400.000002
                Relay_Log_Pos: 1187
        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: 2461
              Relay_Log_Space: 1405
              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: 400
                  Master_UUID: 8fb0aa81-ebd4-11e8-ac5b-0242ac110009
             Master_Info_File: mysql.slave_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: 400
           Master_TLS_Version: 
*************************** 3. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.10.212
                  Master_User: slave
                  Master_Port: 4500
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 2151
               Relay_Log_File: 0ad84f013600-relay-bin-500.000002
                Relay_Log_Pos: 626
        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: 2151
              Relay_Log_Space: 844
              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: 500
                  Master_UUID: b87704d2-ebd5-11e8-a90c-0242ac11000a
             Master_Info_File: mysql.slave_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: 500
           Master_TLS_Version: 
3 rows in set (0.00 sec)

可以看见设置三个的主从同步通道的所有状态信息。
只有【Slave_IO_Running】和【Slave_SQL_Running】都是Yes，则同步是正常的。
如果是No或者Connecting都不行，可查看mysql-error.log，以排查问题。

mysql> show variables like 'log_error%';
+---------------------+--------+
| Variable_name       | Value  |
+---------------------+--------+
| log_error           | stderr |
| log_error_verbosity | 3      |
+---------------------+--------+
2 rows in set

配置完成，则【从库10345】开始自动同步。

若需要单独启动或停止某个同步通道，可使用如下命令：
start slave for channel '300'; //启动名称为300的同步通道
stop slave for channel '300'; //停止名称为300的同步通道

验证数据同步

建库

使用root账号登录【主库300】，创建test3数据库

mysql> CREATE DATABASE test3;
Query OK, 1 row affected (0.00 sec)

mysql> USE test3;
Database changed

建表

在【主库300】中创建user表

CREATE TABLE `user` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) COLLATE utf8mb4_unicode_ci NOT NULL,
  `age` tinyint(3) unsigned NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

新增

在【主库300】中向user表插入一条数据：

mysql> use test3;
Database changed
mysql> INSERT INTO user (id, name, age) VALUES (300, 'Tom', 18);
Database changed
mysql> SELECT * FROM user;
+-----+------+-----+
| id  | name | age |
+-----+------+-----+
| 300 | Tom  |  18 |
+-----+------+-----+
1 row in set (0.00 sec)

在【从库10345】中查询user表数据：

mysql> use test3;
Database changed
mysql> SELECT * FROM user;
+-----+------+-----+
| id  | name | age |
+-----+------+-----+
| 300 | Tom  |  18 |
+-----+------+-----+
1 row in set (0.00 sec)

新增记录同步成功。

更新

在【主库300】中修改刚才插入的数据：

mysql> UPDATE user SET name='Peter' where id=300;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from user;
+-----+-------+-----+
| id  | name  | age |
+-----+-------+-----+
| 300 | Peter |  18 |
+-----+-------+-----+
1 row in set (0.00 sec)

在【从库10345】中查询user表数据：

mysql> select * from user;
+-----+-------+-----+
| id  | name  | age |
+-----+-------+-----+
| 300 | Peter |  18 |
+-----+-------+-----+
1 row in set (0.00 sec)

更新记录同步成功。

删除

在【主库300】中删除刚才更新的数据：

mysql> DELETE FROM user WHERE id=300;
Query OK, 1 row affected (0.00 sec)

mysql> select * from user;
Empty set (0.00 sec)

在【从库10345】中查询user表数据：

mysql> select * from user;
Empty set (0.00 sec)

删除记录同步成功。
注：【主库400】、【主库500】的验证操作与上述类似。

补充：

• 如果【主服务器】重启mysql服务，【从服务器】会等待与【主服务器】重连。当主服务器恢复正常后，从服务器会自动重新连接上主服务器，并正常同步数据。
• 如果某段时间内，【从数据库】服务器异常导致同步中断（可能是同步点位置不匹配），可以尝试以下恢复方法：进入【主数据库】服务器（正常），在bin-log中找到【从数据库】出错前的position，然后在【从数据库】上执行change master，将master_log_file和master_log_pos重新指定后，开始同步。
• 若是不需要同步，登录从库执行：stop slave;
• 若需要单独启动或停止某个同步通道，可使用如下命令：
  start slave for channel '300'; //启动名称为300的同步通道
  stop slave for channel '300'; //停止名称为300的同步通道
• 通常多主一从，主库之间尽量不使用相同的databaseName，避免冲突。