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《mycat结合MySQL双主实现读写分离》要点：
本文介绍了mycat结合MySQL双主实现读写分离，希望对您有用。如果有疑问，可以联系我们。
作者介绍
牛恒博,一线运维人,擅长为中小企业快速实现运维从无到有,再到自动化.现就职于某医疗大数据公司.
服务器拓扑
服务器架构
安装MySQL
创建mysql用户
groupadd mysql
useradd -r -g mysql -s /bin/false mysql
安装MySQL
yum install -y libaio
cd /usr/local/src/
wget http://mirrors.sohu.com/mysql/MySQL-5.7/mysql-5.7.17-linux-glibc2.5-x86_64.tar.gz
tar -zxf mysql-5.7.17-linux-glibc2.5-x86_64.tar.gz
cp -rf mysql-5.7.17-linux-glibc2.5-x86_64 /data/app/mysql-3306
cp -rf mysql-5.7.17-linux-glibc2.5-x86_64 /data/app/mysql-3307
chown -R mysql:mysql /data/app/mysql-3306
chown -R mysql:mysql /data/app/mysql-3307
/data/app/mysql-3306/bin/mysqld --initialize-insecure --user=mysql --basedir=/data/app/mysql-3306 --datadir=/data/app/mysql-3306/data
/data/app/mysql-3307/bin/mysqld --initialize-insecure --user=mysql --basedir=/data/app/mysql-3307 --datadir=/data/app/mysql-3307/data
修改my.cnf
需要修改的参数：?
- server-id：保证每个配置文件唯一
- 两台master的自增长ID必须不同
linux-node2
master
cat > /data/app/mysql-3306/my.cnf<<EOF
[client]
port = 3306
socket = /data/app/mysql-3306/mysql.sock
[mysqld]
port = 3306
user = mysql
server-id = 1
bind-address = 0.0.0.0
basedir = /data/app/mysql-3306
datadir = /data/app/mysql-3306/data
socket = /data/app/mysql-3306/mysql.sock
pid-file = /data/app/mysql-3306/mysql.pid
log-error = /data/app/mysql-3306/mysqld.log
skip-name-resolve
log_bin = mysql-bin
log-slave-updates
auto-increment-increment = 2
auto-increment-offset = 1
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
EOF
chown mysql.mysql /data/app/mysql-3306/my.cnf
slave
cat > /data/app/mysql-3307/my.cnf<<EOF
[client]
port = 3307
socket = /data/app/mysql-3307/mysql.sock
[mysqld]
port = 3307
user = mysql
server-id = 11
bind-address = 0.0.0.0
basedir = /data/app/mysql-3307
datadir = /data/app/mysql-3307/data
socket = /data/app/mysql-3307/mysql.sock
pid-file = /data/app/mysql-3307/mysql.pid
log-error = /data/app/mysql-3307/mysqld.log
skip-name-resolve
log_bin = mysql-bin
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
EOF
chown mysql.mysql /data/app/mysql-3307/my.cnf
linux-node3
master
cat > /data/app/mysql-3306/my.cnf<<EOF
[client]
port = 3306
socket = /data/app/mysql-3306/mysql.sock
[mysqld]
port = 3306
user = mysql
server-id = 2
bind-address = 0.0.0.0
basedir = /data/app/mysql-3306
datadir = /data/app/mysql-3306/data
socket = /data/app/mysql-3306/mysql.sock
pid-file = /data/app/mysql-3306/mysql.pid
log-error = /data/app/mysql-3306/mysqld.log
skip-name-resolve
log_bin = mysql-bin
log-slave-updates
auto-increment-increment = 2
auto-increment-offset = 2
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
EOF
chown mysql.mysql /data/app/mysql-3306/my.cnf
slave
cat > /data/app/mysql-3307/my.cnf<<EOF
[client]
port = 3307
socket = /data/app/mysql-3307/mysql.sock
[mysqld]
port = 3307
user = mysql
server-id = 22
bind-address = 0.0.0.0
basedir = /data/app/mysql-3307
datadir = /data/app/mysql-3307/data
socket = /data/app/mysql-3307/mysql.sock
pid-file = /data/app/mysql-3307/mysql.pid
log-error = /data/app/mysql-3307/mysqld.log
skip-name-resolve
log_bin = mysql-bin
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
EOF
chown mysql.mysql /data/app/mysql-3307/my.cnf
启动MySQL
启动服务
linux-node2和linux-node3都执行如下命令
touch /data/app/mysql-3306/mysqld.log && chown mysql.mysql /data/app/mysql-3306/mysqld.log
sed -i 's#/usr/local/mysql#/data/app/mysql-3306#g' /data/app/mysql-3306/bin/mysqld_safe
/data/app/mysql-3306/bin/mysqld_safe --defaults-file=/data/app/mysql-3306/my.cnf --basedir=/data/app/mysql-3306 --datadir=/data/app/mysql-3306/data --user=mysql &
touch /data/app/mysql-3307/mysqld.log && chown mysql.mysql /data/app/mysql-3307/mysqld.log
sed -i 's#/usr/local/mysql#/data/app/mysql-3307#g' /data/app/mysql-3307/bin/mysqld_safe
/data/app/mysql-3307/bin/mysqld_safe --defaults-file=/data/app/mysql-3307/my.cnf --basedir=/data/app/mysql-3307 --datadir=/data/app/mysql-3307/data --user=mysql &
检查端口
ss -lntup |egrep '3306|3307'
tcp ? ?LISTEN ? ? 0 ? ? ?80 ? ? ? ? ? ? ? ? ? ? *:3306 ? ? ? ? ? ? ? ? ?*:* ? ? ?users:(("mysqld",19973,22))
tcp ? ?LISTEN ? ? 0 ? ? ?80 ? ? ? ? ? ? ? ? ? ? *:3307 ? ? ? ? ? ? ? ? ?*:* ? ? ?users:(("mysqld",20537,22))
配置双主
配置主从
linux-node2
master
cd /data/app/mysql-3306/
./bin/mysql -uroot -p -S mysql.sock -P 3306
mysql> CREATE USER 'repl'@'192.%' IDENTIFIED BY 'mysql';
Query OK,0 rows affected (0.05 sec)
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.%';
Query OK,0 rows affected (0.00 sec)
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File ? ? ? ? ? ? | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | ? ? ?613 | ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
slave
cd /data/app/mysql-3307/
./bin/mysql -uroot -p -S mysql.sock -P 3307
mysql> CHANGE MASTER TO MASTER_HOST='192.168.56.12',? ?-> ? ? ? ? ? ? ? ? ?MASTER_PORT=3306,? ?-> ? ? ? ? ? ? ? ? ?MASTER_USER='repl',? ?-> ? ? ? ? ? ? ? ? ?MASTER_PASSWORD='mysql',? ?-> ? ? ? ? ? ? ? ? ?MASTER_LOG_FILE='mysql-bin.000001',? ?-> ? ? ? ? ? ? ? ? ?MASTER_LOG_POS=613;
Query OK,0 rows affected,2 warnings (0.04 sec)
mysql> start slave;
Query OK,0 rows affected (0.02 sec)
mysql> show slave statusG
*************************** 1. row ***************************
? ? ? ? ? ? ? Slave_IO_State: Waiting for master to send event
? ? ? ? ? ? ? ? ?Master_Host: 192.168.56.12
? ? ? ? ? ? ? ? ?Master_User: repl
? ? ? ? ? ? ? ? ?Master_Port: 3306
? ? ? ? ? ? ? ?Connect_Retry: 60
? ? ? ? ? ? ?Master_Log_File: mysql-bin.000001
? ? ? ? ?Read_Master_Log_Pos: 613
? ? ? ? ? ? ? Relay_Log_File: linux-node2-relay-bin.000002
? ? ? ? ? ? ? ?Relay_Log_Pos: 320
? ? ? ?Relay_Master_Log_File: mysql-bin.000001
? ? ? ? ? ? Slave_IO_Running: Yes
? ? ? ? ? ?Slave_SQL_Running: Yes
linux-node3
master
cd /data/app/mysql-3306/
./bin/mysql -uroot -p -S mysql.sock -P 3306
mysql> CREATE USER 'repl'@'192.%' IDENTIFIED BY 'mysql';
Query OK,0 rows affected (0.00 sec)
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File ? ? ? ? ? ? | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | ? ? ?613 | ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
slave
cd /data/app/mysql-3307/
./bin/mysql -uroot -p -S mysql.sock -P 3307
mysql>
CHANGE MASTER TO MASTER_HOST='192.168.56.13',? ? ? ? ? ? ? ? MASTER_PORT=3306,? ? ? ? ? ? ? ? MASTER_USER='repl',? ? ? ? ? ? ? ? MASTER_PASSWORD='mysql',? ? ? ? ? ? ? ? MASTER_LOG_FILE='mysql-bin.000001',? ? ? ? ? ? ? ? MASTER_LOG_POS=613;
Query OK,0 rows affected (0.02 sec)
mysql> show slave statusG
*************************** 1. row ***************************
? ? ? ? ? ? ? Slave_IO_State: Waiting for master to send event
? ? ? ? ? ? ? ? ?Master_Host: 192.168.56.13
? ? ? ? ? ? ? ? ?Master_User: repl
? ? ? ? ? ? ? ? ?Master_Port: 3306
? ? ? ? ? ? ? ?Connect_Retry: 60
? ? ? ? ? ? ?Master_Log_File: mysql-bin.000001
? ? ? ? ?Read_Master_Log_Pos: 613
? ? ? ? ? ? ? Relay_Log_File: linux-node2-relay-bin.000002
? ? ? ? ? ? ? ?Relay_Log_Pos: 320
? ? ? ?Relay_Master_Log_File: mysql-bin.000001
? ? ? ? ? ? Slave_IO_Running: Yes
? ? ? ? ? ?Slave_SQL_Running: Yes
配置双主
master的binlog位置
linux-node2 master端
d /data/app/mysql-3306/
./bin/mysql -uroot -p -S mysql.sock -P 3306
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File ? ? ? ? ? ? | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | ? ? ?613 | ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
linux-node3 master端
cd /data/app/mysql-3306/
./bin/mysql -uroot -p -S mysql.sock -P 3306
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File ? ? ? ? ? ? | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | ? ? ?613 | ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
linux-node2 master配置跟linux-node3 master同步
mysql> CHANGE MASTER TO MASTER_HOST='192.168.56.13',? ? ? ? ? ? ? ? MASTER_LOG_POS=613;
mysql> start slave;
Query OK,0 rows affected (0.03 sec)
mysql> show slave statusG
*************************** 1. row ***************************
? ? ? ? ? ? ? Slave_IO_State: Waiting for master to send event
? ? ? ? ? ? ? ? ?Master_Host: 192.168.56.13
? ? ? ? ? ? ? ? ?Master_User: repl
? ? ? ? ? ? ? ? ?Master_Port: 3306
? ? ? ? ? ? ? ?Connect_Retry: 60
? ? ? ? ? ? ?Master_Log_File: mysql-bin.000001
? ? ? ? ?Read_Master_Log_Pos: 613
? ? ? ? ? ? ? Relay_Log_File: linux-node2-relay-bin.000002
? ? ? ? ? ? ? ?Relay_Log_Pos: 320
? ? ? ?Relay_Master_Log_File: mysql-bin.000001
? ? ? ? ? ? Slave_IO_Running: Yes
? ? ? ? ? ?Slave_SQL_Running: Yes ? ? ? ?
linux-node3 master配置跟linux-node2 master同步
mysql> CHANGE MASTER TO MASTER_HOST='192.168.56.12',0 rows affected (0.00 sec)
mysql>
mysql> show slave statusG
*************************** 1. row ***************************
? ? ? ? ? ? ? Slave_IO_State: Waiting for master to send event
? ? ? ? ? ? ? ? ?Master_Host: 192.168.56.12
? ? ? ? ? ? ? ? ?Master_User: repl
? ? ? ? ? ? ? ? ?Master_Port: 3306
? ? ? ? ? ? ? ?Connect_Retry: 60
? ? ? ? ? ? ?Master_Log_File: mysql-bin.000001
? ? ? ? ?Read_Master_Log_Pos: 613
? ? ? ? ? ? ? Relay_Log_File: linux-node3-relay-bin.000002
? ? ? ? ? ? ? ?Relay_Log_Pos: 320
? ? ? ?Relay_Master_Log_File: mysql-bin.000001
? ? ? ? ? ? Slave_IO_Running: Yes
? ? ? ? ? ?Slave_SQL_Running: Yes
验证
从linux-node2上验证
在linux-node2 master上创建数据
mysql> create database test;
Query OK,1 row affected (0.01 sec)
mysql> use test;
Database changed
mysql> create table temp(id int,name varchar(64));
Query OK,0 rows affected (0.11 sec)
mysql> insert into temp values(1,'aaa');
Query OK,1 row affected (0.28 sec)
mysql> CREATE TABLE temp2(id INT PRIMARY KEY ?NOT NULL AUTO_INCREMENT,nname VARCHAR(64));
Query OK,0 rows affected (0.01 sec)
mysql> insert into temp2(nname) values('bbb');
Query OK,1 row affected (0.01 sec)
mysql> select * from test.temp;
+------+------+
| id ? | name |
+------+------+
| ? ?1 | aaa ?|
+------+------+
1 row in set (0.01 sec)
在linux-node2 slave上查看数据
mysql> select * from test.temp;
+------+------+
| id ? | name |
+------+------+
| ? ?1 | aaa ?|
+------+------+
1 row in set (0.00 sec)
在linux-node3 master上查看数据
mysql> select * from test.temp;
+------+------+
| id ? | name |
+------+------+
| ? ?1 | aaa ?|
+------+------+
1 row in set (0.00 sec)
在linux-node3 slave上查看数据
mysql> select * from test.temp;
+------+------+
| id ? | name |
+------+------+
| ? ?1 | aaa ?|
+------+------+
1 row in set (0.00 sec)
从linux-node3上验证
在linux-node3 master上创建数据
mysql> use test;
mysql> insert into temp2(nname) values('ddd');
Query OK,1 row affected (0.02 sec)
mysql> ?insert into temp2(nname) values('fff');
Query OK,1 row affected (0.00 sec)
mysql> select * from test.temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
+----+-------+
在linux-node3 slave上查看数据
mysql> select * from test.temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
+----+-------+
3 rows in set (0.00 sec)
在linux-node2 master上查看数据
mysql> select * from test.temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
+----+-------+
3 rows in set (0.00 sec)
在linux-node2 slave上查看数据
mysql> select * from test.temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
+----+-------+
3 rows in set (0.00 sec)
结论
- 在任意一个master端更新数据,其他任意端都可以更新数据
- 两台服务器配置了间隔自增长,数据不同冲突
linux-node1上安装mycat
安装mycat
cd /usr/local/src
wget http://dl.mycat.io/1.6-RELEASE/Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz
tar -zxf Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz
mv mycat /data/app/mycat-1.6
ln -s /data/app/mycat-1.6 /data/app/mycat
修改schema.xml
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 writeHost,重新启动后以切换后的为准,切换记录在配置文件中:dnindex.propertiesswitchType="1"
默认值为1,自动切换
cd /data/app/mycat
cp conf/schema.xml conf/schema.xml.bak
cat > conf/schema.xml <<EOF
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
<schema name="TESTDB" checkSQLschema="true" sqlMaxLimit="100" dataNode="dn1"></schema>
? ?<dataNode name="dn1" dataHost="node1" database="test" />
? ?<dataHost name="node1" maxCon="10" minCon="5" balance="1" writeType="0" dbType="mysql" dbDriver="native" switchType="1">
? ? ? ?<heartbeat>select user()</heartbeat>
? ? ? ?<writeHost host="master1" url="192.168.56.12:3306" user="root" password="mysql">
? ? ? ? ? ?<readHost host="slave2" url="192.168.56.13:3307" user="root" password="mysql" />
? ? ? ?</writeHost>
? ? ? ?<writeHost host="master2" url="192.168.56.13:3306" user="root" password="mysql">
? ? ? ? ? ?<readHost host="slave2" url="192.168.56.13:3307" user="root" password="mysql" />
? ? ? ?</writeHost>
? ?</dataHost>
</mycat:schema>
EOF
启动mycat
./bin/mycat start
ss -lntup |egrep ?'(8066|9066)' ?
tcp ? ?LISTEN ? ? 0 ? ? ?100 ? ? ? ? ? ? ? ? ? :::8066 ? ? ? ? ? ? ? ? :::* ? ? ?users:(("java",16546,79))
tcp ? ?LISTEN ? ? 0 ? ? ?100 ? ? ? ? ? ? ? ? ? :::9066 ? ? ? ? ? ? ? ? :::* ? ? ?users:(("java",75))
验证mycat服务是否正常
在linux-node2-master端配置mycat连接账号
mysql> GRANT ALL PRIVILEGES ON *.* TO root@'192.%' IDENTIFIED BY 'mysql';
Query OK,1 warning (0.07 sec
在mycat服务器上安装mysql服务,但是不启动
步骤省略,详细内容可以参考上面的MySQL安装
使用mysql的客户端连接mycat
cd /data/app/mysql/
./bin/mysql -uroot -p -P 8066 -h 192.168.56.11 ##连接mycat,初始密码123456
mysql> show databases;
+----------+
| DATABASE |
+----------+
| TESTDB ? |
+----------+
1 row in set (0.00 sec)
mysql> use TESTDB;
mysql> insert into temp2(nname) values('eee');
Query OK,1 row affected (0.09 sec)
mysql> insert into temp2(nname) values('ggg');
Query OK,1 row affected (0.01 sec)
linux-node3 slave端查看数据是否同步
mysql> select * from test.temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
| ?5 | eee ? |
| ?7 | ggg ? |
+----+-------+
5 rows in set (0.00 sec)
结果发现数据写入到了linux-node2 slave端
测试
服务自动迁移
关闭linux-node2 master的MySQL服务
mysql> shutdown;
Query OK,0 rows affected (0.01 sec)
shell > ss -lntup |grep 3306
mycat端插入新的数据查看数据是否同步
mysql> insert into temp2(nname) values('mmmm');
Query OK,1 row affected (0.07 sec)
mysql> insert into temp2(nname) values('nnnn');
Query OK,1 row affected (0.01 sec)
linux-node3 slave端查看数据是否同步
mysql> select * from test.temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
| ?5 | eee ? |
| ?7 | ggg ? |
| ?8 | mmmm ?|
| 10 | nnnn ?|
+----+-------+
7 rows in set (0.00 sec)
linux-node2 slave端查看数据是否同步
mysql> select * from test.temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
| ?5 | eee ? |
| ?7 | ggg ? |
+----+-------+
5 rows in set (0.00 sec)
发现因为linux-node2的master端已经挂了,数据不能同步了
数据访问是否正常
登录到mycat服务器上执行如下命令：
mysql> select * from temp2;
+----+-------+
| id | nname |
+----+-------+
| ?1 | bbb ? |
| ?2 | ddd ? |
| ?4 | fff ? |
| ?5 | eee ? |
| ?7 | ggg ? |
| ?8 | mmmm ?|
| 10 | nnnn ?|
+----+-------+
7 rows in set (0.00 sec)
执行多次发现结果一样,说明在一台master端挂掉的情况下,其连接的slave端也被剔除,因此数据完整性可以保证
故障汇总
第一次配置的时候maser端没有配置log-slave-updates,导致node3-slave上没有node2-master端的数据.
解释：
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.
解决办法：
[mysqld]
log-slave-updates
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