Mycat的简单使用主从读写
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Mycat的简单使用（二）
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。
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) |
|---|---|---|---|---|
| 1 | Master1 | m1 | 172.17.0.2 | 1 |
| 2 | Slave1 | s1 | 172.17.0.3 | 2 |
| 3 | Master2 | m2 | 172.17.0.4 | 3 |
| 4 | Slave | s2 | 172.17.0.5 | 4 |
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id | ip地址 | server-id(my.cnf) | 启用二进制日志 | 启用中继日志 |
|---|---|---|---|---|---|---|---|
| 1 | Master1 | m1 | ace8d2729df2 | 172.17.0.2 | 1 | 是 | |
| 2 | Slave1 | s1 | 78f1f8ce6c8b | 172.17.0.3 | 2 | 是 | |
| 3 | Master2 | m2 | 6b3868d2f49d | 172.17.0.4 | 3 | 是 | |
| 4 | Slave | s2 | d99c2936a62d | 172.17.0.5 | 4 | 是 |
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id | ip地址 | server-id(my.cnf) | 启用二进制日志 | 启用中继日志 | MASTER_LOG_FILE | MASTER_LOG_POS |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Master1 | m1 | ace8d2729df2 | 172.17.0.2 | 1 | 是 | 是 | mysql-bin.000003 | 619 |
| 2 | Slave1 | s1 | 78f1f8ce6c8b | 172.17.0.3 | 2 | 是 | |||
| 3 | Master2 | m2 | 6b3868d2f49d | 172.17.0.4 | 3 | 是 | mysql-bin.000003 | 619 | |
| 4 | Slave | s2 | d99c2936a62d | 172.17.0.5 | 4 | 是 |
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_Running、Slave_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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