实战演示MySQL 5.7.17实现主从复制

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主从复制的原理：

分为同步复制和异步复制，实际复制架构中大部分为异步复制。 复制的基本过程如下：

1).Slave上面的IO进程连接上Master，并请求从指定日志文件的指定位置（或者从最开始的日志）之后的日志内容；

2).Master接收到来自Slave的IO进程的请求后，通过负责复制的IO进程根据请求信息读取制定日志指定位置之后的日志信息，返回给Slave 的IO进程。返回信息中除了日志所包含的信息之外，还包括本次返回的信息已经到Master端的bin-log文件的名称以及bin-log的位置；

3).Slave的IO进程接收到信息后，将接收到的日志内容依次添加到Slave端的relay-log文件的最末端，并将读取到的Master端的 bin-log的文件名和位置记录到master-info文件中，以便在下一次读取的时候能够清楚的告诉Master"我需要从某个bin-log的哪个位置开始往后的日志内容，请发给我"；

4).Slave的Sql进程检测到relay-log中新增加了内容后，会马上解析relay-log的内容成为在Master端真实执行时候的那些可执行的内容，并在自身执行。

一、环境准备

操作系统版本：centos 7.2

云服务器架构：

Master(主) ip：192.168.2.70 主机名称：node01 server_id:1

Slave(从) ip：192.168.2.71 主机名称：node02 server_id:2

Slave(从) ip：192.168.2.5 主机名称：node03 server_id:3

其他准备：

每台云服务器配置以下hosts

# vim /etc/hosts

192.168.2.70 node01

192.168.2.71 node02

192.168.2.5 node03

系统时间同步:

#yum install chrony

配置时间同步源：# vi /etc/chrony.conf

# Please consider joining the pool (http://www.pool.ntp.org/join.html).

server 0.rhel.pool.ntp.org iburst

server 1.rhel.pool.ntp.org iburst

# systemctl start chronyd.service #启动

# chronyc sources -v #同步时间源

关闭selinux

关闭firewalld防火墙

准备测试数据库apps.sql

解决依赖关系:yum -y install gcc gcc-c++ ncurses ncurses-devel cmake bison

先移除:rpm -e --nodeps mariadb-libs-5.5.44-2.el7.centos.x86_64

新建目录/mydata/data(建议使用lvm2镜像，实现物理备份)，存放数据库数据

mysql 安装部署请参照http://daisywei.blog.51cto.com/7837970/1896614 (这里不再阐述)

二、SSH密钥登录方式设置

在node01节点192.168.2.70操作：

[root@node01 ~]# ssh-keygen -t rsa[root@node01 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.2.71[root@node01 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.2.5

在node02节点192.168.2.71操作：

[root@node02 ~]# ssh-keygen -t rsa[root@node02 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.2.70[root@node02 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.2.5

在node03节点192.168.2.5操作：

[root@node03 ~]# ssh-keygen -t rsa[root@node03 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.2.70[root@node03 ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.2.71

三、搭建主从复制架构

1、node01、node02、node03安装mysql,并初始化数据库(省略)

2、默认安装mysql有随机生成密码，node01、node02、node3节点上数据库设置管理员密码(测试密码：111111)，同时创建复制使用的账号repl(密码111111)

#授权192.168.2.%网段主机root用户访问任意库，本地登录密码

mysql>  SET PASSWORD = PASSWORD('111111');mysql> UPDATE user SET host='192.168.2.%' where user = 'root';mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhsot' IDENTIFIED BY '111111';mysql> GRANT ALL PRIVILEGES ON *.* TO  'root'@'192.168.2.%' IDENTIFIED BY '111111';mysql> grant replication slave on *.* to 'repl'@'%' identified by '111111'; mysql> FLUSH PRIVILEGES;

3、node01(192.168.2.70)master配置mysql文件my.cnf(修改前建议备份该文件)修改如下内容,修改配置后重启数据库：

[mysqld]datadir = /mydata/data  #数据存放目录socket = /tmp/mysql.sock #socketinnodb_file_per_table = ON  #开启独立的表空间skip_name_resolve = ON   #禁用dns解析log_bin = mysql-bin  #开启日志(日志存储位置尽量不要同数据存储同一磁盘同一目录，这里测试方便不重新指向)relay_log = relay-bin #开启中继日志 (日志存储位置尽量不要同数据存储同一磁盘同一目录，这里测试方便不重新指向)binlog-format = row  #日志格式log-slave-updates = true   # 配置从云服务器的更新写入二进制日志sever_id = 1              #server_id一定要唯一；[root@node01 ~]# systemctl restart mysqld.service #重启服务

注意：日志格式，binlog的格式也有三种：STATEMENT，ROW，MIXED。

mysql> show variables like 'log_%';   #查看日志是否开启

binlog-do-db 和 replicate-ignore-db 必须相同

log_bin、relay_log，二进制日志和中继日志尽量不要跟数据存储放在同一磁盘同一目录，防止硬盘损坏时日志也丢失

4、node01(192.168.2.70)master导入测试数据库apps.sql

mysql> CREATE DATABASE apps;Query OK, 1 row affected (0.00 sec)mysql> use apps;Database changedmysql> source /home/soft/apps.sql

5、node02(192.168.2.71)slave配置mysql文件my.cnf修改如下内容,修改配置后重启数据库：

[mysqld]datadir = /mydata/data  socket = /tmp/mysql.sock #socketinnodb_file_per_table = ON  skip_name_resolve = ON   log_bin = mysql-bin  relay_log = relay-bin binlog-format = row  log-slave-updates = true   sever_id = 2              #relay_log_purge=0           #禁止自动删除中继日志(slave配置文件多了下面这两条），如果是MHA开启此项[root@node02 ~]# systemctl restart mysqld.service #重启服务[root@node02 ~]#mysql -uroot -p111111 -e "set global read_only=1"  #从库只读，不建议写在配置文件中

6、node03(192.168.2.5)slave配置mysql文件my.cnf修改如下内容,修改配置后重启数据库：

[mysqld]datadir = /mydata/data  socket = /tmp/mysql.sock #socketinnodb_file_per_table = ON  skip_name_resolve = ON   log_bin = mysql-bin  relay_log = relay-bin binlog-format = row  log-slave-updates = true   sever_id = 3              #relay_log_purge=0           #禁止自动删除中继日志(slave配置文件多了下面这两条），如果是MHA开启此项[root@node03 ~]# systemctl restart mysqld.service #重启服务[root@node03 ~]#mysql -uroot -p111111 -e "set global read_only=1"  #从库只读，不建议写在配置文件中

7、在node01(192.168.2.70)Master上备份一份完整的数据：

[root@node01 /]# mysqldump -uroot -p111111 -h292.168.2.70 --master-data=2 --single-transaction -R --triggers -A > /home/soft/all.sql;

说明：

--master-data=2代表备份时刻记录master的Binlog位置和Position

--single-transaction意思是获取一致性快照

-R意思是备份存储过程和函数

--triggres的意思是备份触发器

-A代表备份所有的库

查看更多信息mysqldump --help

8、在node01(192.168.2.70)Master上创建复制用户repl（密码111111），并授权访问所有主机:

mysql> grant replication slave on *.* to 'repl'@'%' identified by '111111'; mysql> flush privileges; #刷新缓存

9、查看node01(192.168.2.70)Master主库备份时的binlog名称和位置，MASTER_LOG_FILE和MASTER_LOG_POS：

[root@node01 soft]# head -n 30 /home/soft/all.sql | grep 'CHANGE MASTER TO'-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=154;

10、把node01 Master主库备份all.sql复制到从库node01(192.168.2.71)和node3(192.168.2.5)/home/soft/目录下，并且导入到从库中

[root@node01 /]# scp /home/soft/all.sql root@192.168.2.71:/home/soft/  [root@node01 /]# scp /home/soft/all.sql root@192.168.2.5:/home/soft/

11、从库node02，node3导入all.sql，并设置复制参数

[root@node02 /]# mysql -uroot -p111111 -h292.168.2.71 < /home/soft/all.sql [root@node03 /]# mysql -uroot -p111111 -h292.168.2.5 < /home/soft/all.sql

mysql> CREATE DATABASE apps;mysql> use apps;Database changedmysql> source /home/soft/all.sql

node02和node03，连接mysql，执行以下命令：

[root@node02 /]# mysql -uroot -p111111 -h292.168.2.71

mysql> stop slave;  #暂停从库Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> CHANGE MASTER TO MASTER_HOST='192.168.2.70',MASTER_USER='repl', MASTER_PASSWORD='111111',MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=154; Query OK, 0 rows affected, 2 warnings (0.04 sec)

说明：MASTER_HOST #主库 ，MASTER_USER和MASTER_PASSWORD #复制账号密码 ，CHANGE MASTER TO #还原同步文件和日志

mysql> start slave; #启动复制Query OK, 0 rows affected (0.00 sec)mysql> show slave status\G   #查看复制状态*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.70                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 154               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 320        Relay_Master_Log_File: mysql-bin.000001             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: 154              Relay_Log_Space: 521              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: 4c9775f6-ef61-11e6-9973-5297c04d0733             Master_Info_File: /mydata/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)

======================================================

[root@node03 /]# mysql -uroot -p111111 -h292.168.2.5

mysql> stop slave;  #暂停从库Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> CHANGE MASTER TO MASTER_HOST='192.168.2.70',MASTER_USER='repl', MASTER_PASSWORD='111111',MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=154; Query OK, 0 rows affected, 2 warnings (0.04 sec)说明：MASTER_HOST #主库 ，MASTER_USER和MASTER_PASSWORD #复制账号密码  ，CHANGE MASTER TO #还原同步文件和日志mysql> start slave; #启动复制Query OK, 0 rows affected (0.00 sec)mysql> show slave status\G   #查看复制状态*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.70                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 154               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 320        Relay_Master_Log_File: mysql-bin.000001             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: 154              Relay_Log_Space: 521              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: 4c9775f6-ef61-11e6-9973-5297c04d0733             Master_Info_File: /mydata/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 (0.01 sec)

12、验证复制是否正常！

############主库node01 Master插入一行数据，并查看Position号

mysql> INSERT INTO apps (app_name,url,country) VALUES ('BAIDU','http://www.baidu.com','CN');Query OK, 1 row affected (0.00 sec)mysql> show master status \G*************************** 1. row ***************************             File: mysql-bin.000001         Position: 449     Binlog_Do_DB:  Binlog_Ignore_DB: Executed_Gtid_Set: 1 row in set (0.00 sec)

#######从库node02 slave查看是否已经同步存在，Position号是否与主库master一致

mysql> SELECT * from apps;+----+------------+-------------------------+---------+| id | app_name   | url                     | country |+----+------------+-------------------------+---------+|  1 | QQ APP     | http://im.qq.com/       | CN      ||  2 | 微博 APP   | http://weibo.com/       | CN      ||  3 | 淘宝 APP   | https://www.taobao.com/ | CN      ||  4 | BAIDU      | http://www.baidu.com    | CN      |+----+------------+-------------------------+---------+mysql> show slave status\G*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.70                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 449    #与主库Position一致               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 615        Relay_Master_Log_File: mysql-bin.000001             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: 449              Relay_Log_Space: 816              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: 4c9775f6-ef61-11e6-9973-5297c04d0733             Master_Info_File: /mydata/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)

########从库node03 slave查看是否已经同步存在，Position号是否与主库master一致

mysql> SELECT * from apps;+----+------------+-------------------------+---------+| id | app_name   | url                     | country |+----+------------+-------------------------+---------+|  1 | QQ APP     | http://im.qq.com/       | CN      ||  2 | 微博 APP   | http://weibo.com/       | CN      ||  3 | 淘宝 APP   | https://www.taobao.com/ | CN      ||  4 | BAIDU      | http://www.baidu.com    | CN      |+----+------------+-------------------------+---------+mysql> show slave status\G*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.70                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 449   #与主库Position保持一致               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 615        Relay_Master_Log_File: mysql-bin.000001             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: 449              Relay_Log_Space: 816              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: 4c9775f6-ef61-11e6-9973-5297c04d0733             Master_Info_File: /mydata/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)

四、主从故障切换

1、确保所有主从数据库都开启二进制日志

mysql> show variables like 'log_bin';+---------------+-------+| Variable_name | Value |+---------------+-------+| log_bin       | ON    |+---------------+-------+1 row in set (0.01 sec)

2、确保切换时数据时从库都是最新先把主库node01设为只读：set global read_only=1;并且刷新一下主库log-bin日志

mysql>  show variables like 'read_only';+---------------+-------+| Variable_name | Value |+---------------+-------+| read_only     | ON    |+---------------+-------+1 row in set (0.00 sec)mysql>  flush logs;Query OK, 0 rows affected (0.02 sec)mysql> show master status;+------------------+----------+--------------+------------------+-------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |+------------------+----------+--------------+------------------+-------------------+| mysql-bin.000002 |      154 |              |                  |                   |+------------------+----------+--------------+------------------+-------------------+1 row in set (0.00 sec)

注意：这里的file已经是mysql-bin.000002不是mysql-bin.000001了，Position号是154，不是上面的449了！！！！！

3、确认从库node02，node03的file和pos是否与主库一致。

mysql> show slave status\G;*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.70                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000002     #注意这里与主库是否一致          Read_Master_Log_Pos: 154                  #注意这里与主库是否一致               Relay_Log_File: relay-bin.000004                Relay_Log_Pos: 367        Relay_Master_Log_File: mysql-bin.000002             Slave_IO_Running: Yes            Slave_SQL_Running: Yes

4、以上确认主库node01没有数据更新后，提升node02(192.168.2.71)为主库，node01变为从库

1)node02暂停从库(注意这里也可以暂停node03从库SLAVE，让它依然同步node01)

mysql> STOP SLAVE;Query OK, 0 rows affected (0.01 sec)

2)更改node02为主库master

mysql> RESET MASTER;Query OK, 0 rows affected (0.01 sec)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)

3)关闭新主库node02的只读属性，并创建一个test01数据库(为后面新链接的从库node01和node03是否正常同步)

mysql> SET GLOBAL read_only=0;Query OK, 0 rows affected (0.00 sec)mysql> CREATE DATABASE test01;Query OK, 1 row affected (0.00 sec)

这时新主库的Position为以下:

mysql> SHOW MASTER STATUS;+------------------+----------+--------------+------------------+-------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |+------------------+----------+--------------+------------------+-------------------+| mysql-bin.000001 |      319 |              |                  |                   |+------------------+----------+--------------+------------------+-------------------+1 row in set (0.00 sec)

4)设置node01(原主库)身份为slave,并且更改链接新主库node02信息(注:MASTER_LOG_POS这时应该是老的154，不是创建新test01库后的319)，并启动SLAVE

mysql> RESET SLAVE;Query OK, 0 rows affected (0.00 sec)mysql> CHANGE MASTER TO MASTER_HOST='192.168.2.71',MASTER_USER='repl', MASTER_PASSWORD='111111',MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=154; Query OK, 0 rows affected, 2 warnings (0.02 sec)mysql> START SLAVE;mysql> show slave status\G;  #查看从库状态*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.71                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 319               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 485        Relay_Master_Log_File: mysql-bin.000001             Slave_IO_Running: Yes            Slave_SQL_Running: Yes…………mysql> show databases;+--------------------+| Database           |+--------------------+| information_schema || apps               || mysql              || performance_schema || sys                || test01             |        #test01数据也已经过来了+--------------------+6 rows in set (0.00 sec)

注意:这时查看node03从库，Master_Host依然是node01(192.168.2.70)，但测试验证的数据库test01也依然同步过来了，如果需要更改链接新主库node02，详见下面操作！！

mysql> show slave status\G;*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.70                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 319   #与新主库node02的Position号也保持一致               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 320        Relay_Master_Log_File: mysql-bin.000001             Slave_IO_Running: Yes            Slave_SQL_Running: Yes…………mysql> SHOW DATABASES;+--------------------+| Database           |+--------------------+| information_schema || apps               || mysql              || performance_schema || sys                || test01             |    #新创建的test01库也同步过来+--------------------+6 rows in set (0.00 sec)

**********注意:修改node03从库SLAVE身份，链接新主库node02的信息(注:MASTER_LOG_POS也依然老的154)，修改并重新启动SLAVE*********

mysql> CHANGE MASTER TO MASTER_HOST='192.168.2.71',MASTER_USER='repl', MASTER_PASSWORD='111111',MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=154;Query OK, 0 rows affected, 2 warnings (0.01 sec)mysql> START SLAVE;Query OK, 0 rows affected (0.00 sec)mysql> show slave status\G;*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.2.71                  Master_User: repl                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000001          Read_Master_Log_Pos: 319   #与新主库node02的Position号也保持一致               Relay_Log_File: relay-bin.000002                Relay_Log_Pos: 320        Relay_Master_Log_File: mysql-bin.000001             Slave_IO_Running: Yes            Slave_SQL_Running: Yes…………mysql> SHOW DATABASES;+--------------------+| Database           |+--------------------+| information_schema || apps               || mysql              || performance_schema || sys                || test01             |    #新创建的test01库也同步过来+--------------------+6 rows in set (0.00 sec)

5、再次验证数据，在node02(192.168.2.71)新主库的apps库apps表中，再插入一条新记录，查看是否同步至其他从库

node02主库上执行以下命令:

mysql> USE apps;Database changedmysql> INSERT INTO apps (app_name,url,country) VALUES ('XINLANG','http://www.sina.com.cn','CN');Query OK, 1 row affected (0.00 sec)mysql> SELECT * FROM apps;+----+------------+-------------------------+---------+| id | app_name   | url                     | country |+----+------------+-------------------------+---------+|  1 | QQ APP     | http://im.qq.com/       | CN      ||  2 | 微博 APP   | http://weibo.com/       | CN      ||  3 | 淘宝 APP   | https://www.taobao.com/ | CN      ||  4 | BAIDU      | http://www.baidu.com    | CN      ||  5 | XINLANG    | http://www.sina.com.cn  | CN      |+----+------------+-------------------------+---------+5 rows in set (0.00 sec)

查看从库node01、node03节点，apps表是否也成功插入数据，得到如下结果:

mysql>  SELECT * FROM apps;+----+------------+-------------------------+---------+| id | app_name   | url                     | country |+----+------------+-------------------------+---------+|  1 | QQ APP     | http://im.qq.com/       | CN      ||  2 | 微博 APP   | http://weibo.com/       | CN      ||  3 | 淘宝 APP   | https://www.taobao.com/ | CN      ||  4 | BAIDU      | http://www.baidu.com    | CN      ||  5 | XINLANG    | http://www.sina.com.cn  | CN      |+----+------------+-------------------------+---------+5 rows in set (0.00 sec)

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