Mysql双主双从（实战干货，好文章！！）-技术圈

1.机器说明

因为主2，从2，都是通过同一个镜像生成的系统，所以mysql的 server-uuid 是一样的，在配置前，需要做以下操作

重命名 /var/lib/mysql/auto.cnf 文件

mv auto.cnf auto.cnf.bak

重启mysql 重新生成 auto.cnf 文件

因为之前配置过 ali-shuidi01,ali-shuidi02的主从关系，所以先将两者之前的主从关系取消，在master1上执行

mysql> stop slave;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> reset master;
Query OK, 0 rows affected (0.01 sec)

2. master1 配置文件修改

vim /etc/my.cnf

#主服务器唯一ID
server-id=1
#启用二进制日志
log-bin=mysql-bin
# 设置不要复制的数据库(可设置多个)
binlog-ignore-db=mysql
binlog-ignore-db=information_schema
binlog-ignore-db=performance_schema
binlog-ignore-db=sys
#设置需要复制的数据库
binlog-do-db=copydb2
#设置logbin格式
binlog_format=STATEMENT
# 在作为从数据库的时候，有写入操作也要更新二进制日志文件
log-slave-updates
#表示自增长字段每次递增的量，指自增字段的起始值，其默认值是1，取值范围是1 .. 65535
auto-increment-increment=2
# 表示自增长字段从哪个数开始，指字段一次递增多少，他的取值范围是1 .. 65535
auto-increment-offset=1

3. master2 配置文件修改

vim /etc/my.cnf

#主服务器唯一ID
server-id=3
#启用二进制日志
log-bin=mysql-bin
# 设置不要复制的数据库(可设置多个)
binlog-ignore-db=mysql
binlog-ignore-db=information_schema
binlog-ignore-db=performance_schema
binlog-ignore-db=sys
#设置需要复制的数据库
binlog-do-db=copydb2
#设置logbin格式
binlog_format=STATEMENT
# 在作为从数据库的时候，有写入操作也要更新二进制日志文件
log-slave-updates
#表示自增长字段每次递增的量，指自增字段的起始值，其默认值是1，取值范围是1 .. 65535
auto-increment-increment=2
# 表示自增长字段从哪个数开始，指字段一次递增多少，他的取值范围是1 .. 65535
auto-increment-offset=2

4. slave1 配置文件修改

vim /etc/my.cnf

#从服务器唯一ID
server-id=2
#启用中继日志
relay-log=mysql-relay

5. slave2配置文件修改

vim /etc/my.cnf

#从服务器唯一ID
server-id=4 #启用中继日志
relay-log=mysql-relay

6. 双主机、双从机重启 mysql 服务, 主机从机都关闭防火墙

[root@shuidi01 etc]# systemctl restart mysqld
[root@shuidi01 etc]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since 一 2020-03-30 20:38:23 CST; 6s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 9985 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 9946 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 9990 (mysqld)
CGroup: /system.slice/mysqld.service
└─9990 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
3月 30 20:38:22 shuidi01 systemd[1]: Starting MySQL Server...
3月 30 20:38:23 shuidi01 systemd[1]: Started MySQL Server.

[root@shuidi02 etc]# systemctl restart mysqld
[root@shuidi02 etc]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since 一 2020-03-30 20:39:10 CST; 7s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 868 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 845 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 873 (mysqld)
CGroup: /system.slice/mysqld.service
└─873 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
3月 30 20:39:09 shuidi02 systemd[1]: Starting MySQL Server...
3月 30 20:39:10 shuidi02 systemd[1]: Started MySQL Server.

[root@shuidi03 etc]# systemctl restart mysqld
[root@shuidi03 etc]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since 一 2020-03-30 20:39:42 CST; 5s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 8507 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 8485 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 8512 (mysqld)
CGroup: /system.slice/mysqld.service
└─8512 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
3月 30 20:39:41 shuidi03 systemd[1]: Starting MySQL Server...
3月 30 20:39:42 shuidi03 systemd[1]: Started MySQL Server.

[root@shuidi04 etc]# systemctl restart mysqld
[root@shuidi04 etc]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since 一 2020-03-30 20:40:13 CST; 8s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 8861 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 8839 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 8866 (mysqld)
CGroup: /system.slice/mysqld.service
└─8866 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
3月 30 20:40:12 shuidi04 systemd[1]: Starting MySQL Server...
3月 30 20:40:13 shuidi04 systemd[1]: Started MySQL Server.

7. 在两台主机上建立账户并授权 slave

master1:

mysql> GRANT REPLICATION SLAVE ON *.* TO 'slave'@'%' IDENTIFIED BY 'Zan_666888';
Query OK, 0 rows affected, 1 warning (0.00 sec)
#查询Master1的状态
mysql> show master status;
+------------------+----------+--------------+-------------------------------------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+-------------------------------------------------+-------------------+
| mysql-bin.000002 | 435 | copydb2 | mysql,information_schema,performance_schema,sys | |
+------------------+----------+--------------+-------------------------------------------------+-------------------+
1 row in set (0.00 sec)

master2:

mysql> GRANT REPLICATION SLAVE ON *.* TO 'slave'@'%' IDENTIFIED BY 'Zan_666888';
Query OK, 0 rows affected, 1 warning (0.01 sec)
#查询Master2的状态
mysql> show master status;
+------------------+----------+--------------+-------------------------------------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+-------------------------------------------------+-------------------+
| mysql-bin.000001 | 435 | copydb2 | mysql,information_schema,performance_schema,sys | |
+------------------+----------+--------------+-------------------------------------------------+-------------------+
1 row in set (0.00 sec)

#分别记录下File和Position的值

#执行完此步骤后不要再操作主服务器MYSQL，防止主服务器状态值变化

8. 在从机上配置需要复制的主机

Slava1 复制 Master1，Slava2 复制 Master2

#复制主机的命令
CHANGE MASTER TO MASTER_HOST='主机的IP地址',
MASTER_USER='slave',
MASTER_PASSWORD='123123',
MASTER_LOG_FILE='mysql-bin.具体数字',MASTER_LOG_POS=具体值;

slave1:

CHANGE MASTER TO MASTER_HOST='172.16.94.131',
MASTER_USER='slave',
MASTER_PASSWORD='Zan_666888',
MASTER_LOG_FILE='mysql-bin.000002',MASTER_LOG_POS=435;

slave2:

CHANGE MASTER TO MASTER_HOST='172.16.94.133',
MASTER_USER='slave',
MASTER_PASSWORD='Zan_666888',
MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=435;

#启动两台从服务器复制功能

slave1:

mysql> start slave;
#查看从服务器状态
show slave status\G;

slave2:

mysql> start slave; #查看从服务器状态 show slave status\G;

#下面两个参数都是Yes，则说明主从配置成功！

# Slave_IO_Running: Yes

# Slave_SQL_Running: Yes

9. 两个主机互相复制

Master2 复制 Master1，Master1 复制 Master2

master2:

mysql> CHANGE MASTER TO MASTER_HOST='172.16.94.131',
-> MASTER_USER='slave',
-> MASTER_PASSWORD='Zan_666888',
-> MASTER_LOG_FILE='mysql-bin.000002',MASTER_LOG_POS=435;
Query OK, 0 rows affected, 2 warnings (0.02 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status\G;

master1:

mysql> CHANGE MASTER TO MASTER_HOST='172.16.94.133',
-> MASTER_USER='slave',
-> MASTER_PASSWORD='Zan_666888',
-> MASTER_LOG_FILE='mysql-bin.000001',MASTER_LOG_POS=435;
Query OK, 0 rows affected, 2 warnings (0.02 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status\G;

#下面两个参数都是Yes，则说明主从配置成功！

# Slave_IO_Running: Yes

# Slave_SQL_Running: Yes

10. Master1 主机新建库、新建表、insert 记录，Master2 和从机复制

mysql> CREATE DATABASE copydb2;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| copydb |
| copydb2 |
| mysql |
| nacos_config |
| performance_schema |
| seata |
| seata_account |
| seata_order |
| seata_storage |
| sys |
+--------------------+
11 rows in set (0.00 sec)
mysql> use copydb2;
Database changed
mysql> CREATE TABLE mytbl(id INT,NAME VARCHAR(20));
Query OK, 0 rows affected (0.01 sec)
mysql> INSERT INTO mytbl VALUES(1,'zhang3');
Query OK, 1 row affected (0.01 sec)
mysql> select * from mytbl;
+------+--------+
| id | NAME |
+------+--------+
| 1 | zhang3 |
+------+--------+
1 row in set (0.00 sec)

四个节点数据均实现了同步

11.如何停止从服务复制功能

stop slave;

如何重新配置主从

stop slave; reset master;

12.修改 Mycat 的配置文件
/usr/local/mycat/conf/schema.xml

修改<dataHost>的balance属性，通过此属性配置读写分离的类型

负载均衡类型，目前的取值有4 种：

（1）balance="0", 不开启读写分离机制，所有读操作都发送到当前可用的 writeHost 上。

（2）balance="1"，全部的 readHost 与 stand by writeHost 参与 select 语句的负载均衡，简单地说，当双主双从

模式(M1->S1，M2->S2，并且 M1 与 M2 互为主备)，正常情况下，M2,S1,S2 都参与 select 语句的负载均衡。

（3）balance="2"，所有读操作都随机的在 writeHost、readhost 上分发。

（4）balance="3"，所有读请求随机的分发到 readhost 执行，writerHost 不负担读压力

为了双主双从读写分离balance设置为1

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1">
</schema>
<dataNode name="dn1" dataHost="host1" database="copydb2" />
<dataHost name="host1" maxCon="1000" minCon="10" balance="1"
writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100">
<heartbeat>select user()</heartbeat>
<writeHost host="hostM1" url="172.16.94.131:3306" user="root"
password="Zan_123456">
<readHost host="hostS1" url="172.16.94.132:3306" user="root" password="Zan_123456" />
</writeHost>
<writeHost host="hostM2" url="172.16.94.133:3306" user="root"
password="Zan_123456">
<readHost host="hostS2" url="172.16.94.134:3306" user="root" password="Zan_123456" />
</writeHost>
</dataHost>
</mycat:schema>

#balance="1": 全部的readHost与stand by writeHost参与select语句的负载均衡。

#writeType="0": 所有写操作发送到配置的第一个writeHost，第一个挂了切到还生存的第二个

#writeType="1"，所有写操作都随机的发送到配置的 writeHost，1.5 以后废弃不推荐

#writeHost，重新启动后以切换后的为准，切换记录在配置文件中:dnindex.properties 。

#switchType="1": 1 默认值，自动切换。

# -1 表示不自动切换

# 2 基于 MySQL 主从同步的状态决定是否切换。

13.启动 Mycat,验证读写分离

[root@shuidi01 bin]# ./mycat stop
Stopping Mycat-server...
Mycat-server was not running.
[root@shuidi01 bin]# ./mycat start
Starting Mycat-server...

#登录mycat
mysql -umycat -pzan123456 -P 8066 -h 127.0.0.1
#插入数据
mysql> show databases;
+----------+
| DATABASE |
+----------+
| TESTDB |
+----------+
1 row in set (0.00 sec)
mysql> use TESTDB;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables;
+-------------------+
| Tables_in_copydb2 |
+-------------------+
| mytbl |
+-------------------+
1 row in set (0.00 sec)
mysql> INSERT INTO mytbl VALUES(2,@@hostname);
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> select * from mytbl;
+------+----------+
| id | NAME |
+------+----------+
| 1 | zhang3 |
| 2 | shuidi03 |
+------+----------+
2 rows in set (0.00 sec)
mysql> select * from mytbl;
+------+----------+
| id | NAME |
+------+----------+
| 1 | zhang3 |
| 2 | shuidi02 |
+------+----------+
2 rows in set (0.00 sec)
mysql> select * from mytbl;
+------+----------+
| id | NAME |
+------+----------+
| 1 | zhang3 |
| 2 | shuidi04 |
+------+----------+
2 rows in set (0.00 sec)

#在Mycat里查询mytbl表,可以看到查询语句在Master2（shuidi03）、Slava1（shuidi02）、Slava2（shuidi04）主从三个主机间切换

14.抗风险能力

#停止数据库Master1

[root@shuidi01 logs]# systemctl stop mysqld
[root@shuidi01 logs]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: inactive (dead) since 一 2020-03-30 21:31:28 CST; 4s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 9985 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 9946 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 9990 (code=exited, status=0/SUCCESS)
3月 30 20:38:22 shuidi01 systemd[1]: Starting MySQL Server...
3月 30 20:38:23 shuidi01 systemd[1]: Started MySQL Server.
3月 30 21:31:16 shuidi01 systemd[1]: Stopping MySQL Server...
3月 30 21:31:28 shuidi01 systemd[1]: Stopped MySQL Server.

#在Mycat里插入数据依然成功，Master2自动切换为写主机

mysql> INSERT INTO mytbl VALUES(3,@@hostname);
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> select * from mytbl;
+------+----------+
| id | NAME |
+------+----------+
| 1 | zhang3 |
| 2 | shuidi04 |
| 3 | shuidi04 |
+------+----------+
3 rows in set (0.00 sec)

#启动数据库Master1

[root@shuidi01 logs]# systemctl start mysqld
[root@shuidi01 logs]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: active (running) since 一 2020-03-30 21:33:39 CST; 2s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 3527 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
Process: 3473 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
Main PID: 3531 (mysqld)
CGroup: /system.slice/mysqld.service
└─3531 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
3月 30 21:33:38 shuidi01 systemd[1]: Starting MySQL Server...
3月 30 21:33:39 shuidi01 systemd[1]: Started MySQL Server.

mysql> select * from mytbl;
+------+----------+
| id | NAME |
+------+----------+
| 1 | zhang3 |
| 2 | shuidi01 |
| 3 | shuidi01 |
+------+----------+
3 rows in set (0.00 sec)
mysql> select * from mytbl;
+------+----------+
| id | NAME |
+------+----------+
| 1 | zhang3 |
| 2 | shuidi02 |
| 3 | shuidi02 |
+------+----------+
3 rows in set (0.00 sec)
mysql> select * from mytbl;
+------+----------+
| id | NAME |
+------+----------+
| 1 | zhang3 |
| 2 | shuidi04 |
| 3 | shuidi04 |
+------+----------+
3 rows in set (0.00 sec)

#在Mycat里查询mytbl表,可以看到查询语句在Master1（shuidi01）、Slava1（shuidi02）、Slava2（shuidi04）

主从三个主机间切换

Master1、Master2 互做备机，负责写的主机宕机，备机切换负责写操作，保证数据库读写分离高

可用性。