Mycat的简单使用主从读写

Posted 牛哄哄的柯南

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主从读写分离

分别向主数据库 和从数据库 插入不一样的数据
在mycat客户端查询数据,发现都是写数据库的内容
修改Mycat的配置文件schema.xml的节点的balance属性

1. 当balance=0 时,不开启读写分离,所有读操作都发生在当前的writeHost上
2. 当balance=1 ,所有读操作都随机发送到当前的writeHost对应的readHost和备用的writeHos都参与select语句的负载均衡,简单的说当双主双从模式(M1->S1 ,M2-S2 M2和M2互为主备)
3. 当balance=2,所有的读操作都随机发送到所有的writeHost,readHost上
4. 当balance=3 ,所有的读操作都只发送到writeHost(db1)的readHost(db2)上

生产当中应该使用 1或者3,此处为了演示切换的效果设置balance="2"

<?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="testdb" />



    <dataHost name="host1" maxCon="1000" minCon="10" balance="2"
              writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
        <heartbeat>select user()</heartbeat>

        <!--can have multi write hosts -->
        <writeHost host="hostM1" url="172.17.0.2:3306" user="root"   password="123456">
            <!-- can have multi read hosts -->
            <readHost host="hostS1" url="172.17.0.3:3306" user="root" password="123456" />
        </writeHost>
    </dataHost>






</mycat:schema>

使用客户端连接mycat查询数据

[root@mycat ~]# mysql -umycat -p123456 -h 127.0.0.1 -P 8066
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MySQL connection id is 4
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\\h' for help. Type '\\c' to clear the current input statement.

MySQL [(none)]> 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 [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.01 sec)

MySQL [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.01 sec)

MySQL [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.00 sec)

MySQL [TESTDB]> select * from test_table;
+----+--------------+
| id | name         |
+----+--------------+
|  1 | 订单信息     |
|  2 | 读机器       |
+----+--------------+
2 rows in set (0.00 sec)

双主双从读写分离

原理

一个主机ml用于处理所有写请求,它的从机s1和另一台主机m2还有它的从机s2负责所有读请
求。当m1主机宕机后,m2主机负责写请求,ml、m2互为备机。架构图如下。

在这里插入图片描述

配置数据库

此处重新准备数据库,使用docker安装如下四个mysql容器(可以删除db1、db2两个容器以释放虚拟机压力)

序号角色容器名ip地址server-id(my.cnf)
1Master1m1172.17.0.21
2Slave1s1172.17.0.32
3Master2m2172.17.0.43
4Slaves2172.17.0.54

删除上述db1、db2释放压力

[root@mycat ~]# docker stop db1  && docker rm db1 && docker stop db2  && docker rm db2
db1
db1
db2
db2
[root@mycat ~]# 

创建四个配置文件

创建配置文件目录:

#创建配置文件
[root@mycat ~]# mkdir -p /root/dbcnf

#创建四个配置文件
[root@mycat ~]# touch /root/dbcnf/master1.cnf
[root@mycat ~]# touch /root/dbcnf/master2.cnf
[root@mycat ~]# touch /root/dbcnf/slave1.cnf
[root@mycat ~]# touch /root/dbcnf/slave2.cnf
[root@mycat ~]# 

配置Master1(M1)

修改/root/dbcnf/master1.cnf配置文件添加如下配置:

[mysqld]
#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
#设置需要复制的数据库
binlog-do-db=testdb
#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

使用上述文件创建容器:

[root@mycat ~]# docker run --name m1 -p 3316:3306 -v /root/dbcnf/master1.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
ace8d2729df2f7084c277fba06d18c17725d21a08c5eed6c676c7f890075523f
[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED         STATUS         PORTS                                                  NAMES
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   5 seconds ago   Up 4 seconds   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1
[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  m1
172.17.0.2
[root@mycat ~]# 

通过docker命令查看到m1容器的ip地址为172.17.0.2,填入上述准备的表格中

关于mysql中部分配置的说明:
1、关于log-slave-updates()
从库开启log-bin参数,如果直接往从库写数据,是可以记录log-bin日志的,但是从库通过I0线程读取主库二进制日志文件,然后通过SQL线程写入的数据,是不会记录binlog日志的。也就是说从库从主库上复制的数据,是不写入从库的binlog日志的。所以从库做为其他从库的主库时需要在配置文件中添加log-slave-updates参数。
2、关于binlog-format
mysql复制主要有三种方式:
基于SQL语句的复制(statement-based replication, SBR),
基于行的复制(row-based replication, RBR),
混合模式复制(mixed-based replication, MBR)。对应的,
binlog的格式也有三种:STATEMENT,ROW,MIXED。
① STATEMENT模式(SBR)
每一条会修改数据的sql语句会记录到binlog中。优点是并不需要记录每一条sql语句和每一行的数据变化,减少了binlog日志量,节约IO,提高性能。缺点是在某些情况下会导致master-slave中的数据不一致(如sleep()函数, last_insert_id(),以及user-defined functions(udf)等会出现问题)
② ROW模式(RBR)
不记录每条sql语句的上下文信息,仅需记录哪条数据被修改了,修改成什么样了。而且不会出现某些特定情况下的存储过程、或function、或trigger的调用和触发无法被正确复制的问题。缺点是会产生大量的日志,尤其是alter table的时候会让日志暴涨。
③ MIXED模式(MBR)
以上两种模式的混合使用,一般的复制使用STATEMENT模式保存binlog,对于STATEMENT模式无法复制的操作使用ROW模式保存binlog,MySQL会根据执行的SQL语句选择日志保存方式。

配置Slave1(S1)

保持原配置/root/dbcnf/slave1.cnf不动即可

[mysqld]

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

使用上述文件创建容器并查看ip

[root@mycat ~]# vi /root/dbcnf/slave1.cnf 

[root@mycat ~]# docker run --name s1 -p 3326:3306 -v /root/dbcnf/slave1.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
78f1f8ce6c8b1d6d4216ac2de432a95b39fee99c3bd689d1326bb9399a255d8c

[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED          STATUS          PORTS                                                  NAMES
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   5 seconds ago    Up 3 seconds    33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   12 minutes ago   Up 12 minutes   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1

[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  s1
172.17.0.3
[root@mycat ~]# 

创建Master2(M2)配置文件并创建数据库

创建/root/dbcnf/master2.cnf配置文件并添加如下配置:
同Master1相似,需要修改server-id(为3)、和auto_increment_offset配置

[mysqld]
#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
#设置需要复制的数据库
binlog-do-db=testdb
#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

使用上述文件创建容器并查看ip

[root@mycat ~]# vi /root/dbcnf/master2.cnf

[root@mycat ~]# docker run --name m2 -p 3336:3306 -v /root/dbcnf/master2.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
d567f78b546e63eecf172b36d648f31868632b632fbad230b570d812078459f8

[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED          STATUS          PORTS                                                  NAMES
d567f78b546e   mysql:5.7   "docker-entrypoint.s…"   9 seconds ago    Up 4 seconds    33060/tcp, 0.0.0.0:3336->3306/tcp, :::3336->3306/tcp   m2
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   4 minutes ago    Up 3 minutes    33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   16 minutes ago   Up 16 minutes   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1

[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  m2
172.17.0.4

[root@mycat ~]# 

创建Slave2(S2)配置文件并创建数据库

创建/root/dbcnf/slave2.cnf配置文件并添加如下配置(同Slave1一样即可),修改server-id

[mysqld]

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

使用上述文件创建容器并查看ip

[root@mycat ~]# vim /root/dbcnf/slave2.cnf 

[root@mycat ~]# docker run --name s2 -p 3346:3306 -v /root/dbcnf/slave2.cnf:/etc/mysql/my.cnf -e MYSQL_ROOT_PASSWORD=123456 -d mysql:5.7
f2706a827e15c2443e4056793a9b58370e528148d279546edc677a833a6611fb

[root@mycat ~]# docker ps
CONTAINER ID   IMAGE       COMMAND                  CREATED          STATUS          PORTS                                                  NAMES
f2706a827e15   mysql:5.7   "docker-entrypoint.s…"   5 seconds ago    Up 2 seconds    33060/tcp, 0.0.0.0:3346->3306/tcp, :::3346->3306/tcp   s2
d567f78b546e   mysql:5.7   "docker-entrypoint.s…"   8 minutes ago    Up 8 minutes    33060/tcp, 0.0.0.0:3336->3306/tcp, :::3336->3306/tcp   m2
78f1f8ce6c8b   mysql:5.7   "docker-entrypoint.s…"   12 minutes ago   Up 12 minutes   33060/tcp, 0.0.0.0:3326->3306/tcp, :::3326->3306/tcp   s1
ace8d2729df2   mysql:5.7   "docker-entrypoint.s…"   24 minutes ago   Up 24 minutes   33060/tcp, 0.0.0.0:3316->3306/tcp, :::3316->3306/tcp   m1

[root@mycat ~]# docker inspect --format '{{ .NetworkSettings.IPAddress }}'  s2
172.17.0.5
[root@mycat ~]# 

至此,四台mysql机器(实际是容器)的环境信息如下:

序号角色容器名容器idip地址server-id(my.cnf)启用二进制日志启用中继日志
1Master1m1ace8d2729df2172.17.0.21
2Slave1s178f1f8ce6c8b172.17.0.32
3Master2m26b3868d2f49d172.17.0.43
4Slaves2d99c2936a62d172.17.0.54

在两台主机上建立主从复制账户

在两个mysql主机上(M1、M2)建立帐户并授权。CREATE USER 'slave'@'%' IDENTIFIED BY '123456'; GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%';

具体操作如下:

mysql客户端登录连接m1(IP:172.17.0.2)创建slave用户,并查询master状态

[root@mycat ~]# mysql -uroot -p123456 -h 172.17.0.2 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MySQL connection id is 2
Server version: 5.7.34-log MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\\h' for help. Type '\\c' to clear the current input statement.

MySQL [(none)]> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%';
Query OK, 0 rows affected (0.01 sec)

MySQL [(none)]> show master status;
+------------------+----------+--------------+--------------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB         | Executed_Gtid_Set |
+------------------+----------+--------------+--------------------------+-------------------+
| mysql-bin.000003 |      619 | testdb       | mysql,information_schema |                   |
+------------------+----------+--------------+--------------------------+-------------------+
1 row in set (0.00 sec)

MySQL [(none)]> 

mysql客户端登录连接m2(ip:172.17.0.4)创建slave用户,并查询master状态

[root@mycat ~]# mysql -uroot -p123456 -h 172.17.0.4 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MySQL connection id is 2
Server version: 5.7.34-log MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\\h' for help. Type '\\c' to clear the current input statement.

MySQL [(none)]> CREATE USER 'slave'@'%' IDENTIFIED BY '123456';
Query OK, 0 rows affected (0.06 sec)

MySQL [(none)]> GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'slave'@'%';
Query OK, 0 rows affected (0.01 sec)

MySQL [(none)]> show master status;
+------------------+----------+--------------+--------------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB         | Executed_Gtid_Set |
+------------------+----------+--------------+--------------------------+-------------------+
| mysql-bin.000003 |      619 | testdb       | mysql,information_schema |                   |
+------------------+----------+--------------+--------------------------+-------------------+
1 row in set (0.00 sec)

MySQL [(none)]> 

配置完两个Master后通过查询可以知道Log_File和Log_POS的值为下述内容。

序号角色容器名容器idip地址server-id(my.cnf)启用二进制日志启用中继日志MASTER_LOG_FILEMASTER_LOG_POS
1Master1m1ace8d2729df2172.17.0.21mysql-bin.000003619
2Slave1s178f1f8ce6c8b172.17.0.32
3Master2m26b3868d2f49d172.17.0.43mysql-bin.000003619
4Slaves2d99c2936a62d172.17.0.54

分别记录下File和Position的值后,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

在从机上配置需要复制的主机

Slave1(s1) 复制 Master1(m1),Slave2(s2) 复制 Master2(m2)
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;

进入Slave1(s1)执行 复制主机的命令,并启动从机的slave功能

CHANGE MASTER TO MASTER_HOST='172.17.0.2', MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.3 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MySQL connection id is 2
Server version: 5.7.34 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\\h' for help. Type '\\c' to clear the current input statement.

MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.2',
    -> MASTER_USER='slave',
    -> MASTER_PASSWORD='123456',
    -> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.04 sec)

MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)


MySQL [(none)]> show slave status\\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.17.0.2
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 619
               Relay_Log_File: mysql-relay.000002
                Relay_Log_Pos: 320
        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: 619
              Relay_Log_Space: 523
              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: 1
                  Master_UUID: 306d7a6c-cf33-11eb-8ea3-0242ac110002
             Master_Info_File: /var/lib/mysql/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)

ERROR: No query specified

MySQL [(none)]> 

进入Slave2(s2)执行 复制主机的命令,并启动从机的slave功能

复制的是M2(IP:172.17.0.4)
CHANGE MASTER TO MASTER_HOST='172.17.0.4', MASTER_USER='slave', MASTER_PASSWORD='123456', MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.5 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MySQL connection id is 2
Server version: 5.7.34 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\\h' for help. Type '\\c' to clear the current input statement.

MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.4',
    -> MASTER_USER='slave',
    -> MASTER_PASSWORD='123456',
    -> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.05 sec)



MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> show slave status\\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.17.0.4
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 619
               Relay_Log_File: mysql-relay.000002
                Relay_Log_Pos: 320
        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: 619
              Relay_Log_Space: 523
              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: 3
                  Master_UUID: 687b8bda-cf38-11eb-956e-0242ac110004
             Master_Info_File: /var/lib/mysql/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)

ERROR: No query specified

MySQL [(none)]> 

Slave_IO_RunningSlave_SQL_Running两个参数都是Yes,则说明主从配置成功!
如果显示Connecting可以再执行一次show slave status\\G;

配置两个主机相互备份

Master2(db3) 复制 Master1(db1),Master1(db1) 复制 Master2(db3) 步骤如下:
1、在Master1中配置配置复制命令
2、启动Master1的主从复制功能
3、查看Master1的slave状态
4、在Master2中配置配置复制命令
5、启动Master2的主从复制功能
6、查看Master2的slave状态

具体执行过程如下:
在Master1(IP:172.17.0.2)中配置配置复制命令,复制Master2(IP:172.17.0.4)

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.2 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MySQL connection id is 4
Server version: 5.7.34-log MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\\h' for help. Type '\\c' to clear the current input statement.

MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.4',
    -> MASTER_USER='slave',
    -> MASTER_PASSWORD='123456',
    -> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.04 sec)

MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> show slave status\\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.17.0.4
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 619
               Relay_Log_File: ace8d2729df2-relay-bin.000002
                Relay_Log_Pos: 320
        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: 619
              Relay_Log_Space: 534
              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: 3
                  Master_UUID: 687b8bda-cf38-11eb-956e-0242ac110004
             Master_Info_File: /var/lib/mysql/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)

ERROR: No query specified

在Master2(IP:172.17.0.4)中配置配置复制命令,复制Master1(IP:172.17.0.2)

[root@mycat ~]# mysql -uroot -p123456 -h172.17.0.4 -P3306
Welcome to the MariaDB monitor.  Commands end with ; or \\g.
Your MySQL connection id is 5
Server version: 5.7.34-log MySQL Community Server (GPL)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\\h' for help. Type '\\c' to clear the current input statement.

MySQL [(none)]> CHANGE MASTER TO MASTER_HOST='172.17.0.2',
    -> MASTER_USER='slave',
    -> MASTER_PASSWORD='123456',
    -> MASTER_LOG_FILE='mysql-bin.000003',MASTER_LOG_POS=619;
Query OK, 0 rows affected, 2 warnings (0.03 sec)

MySQL [(none)]> start slave;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> show slave status\\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.17.0.2
                  Master_User: slave
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000003
          Read_Master_Log_Pos: 619
               Relay_Log_File: 6b3868d2f49d-relay-bin.000002
                Relay_Log_Pos: 320
        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: 619
              Relay_Log_Space: 534
              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: 
              

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