MySQL主从配置

一、安装MySQL

可参考LAMP配置进行安装

二、配置从MySQL

//当搭建好一个跑3306端口的MySQL后，再搭建一个3307端口的MySQL2
[root@localhost ~]# cd /usr/local/
[root@localhost local]# cp -r mysql mysql_2
[root@localhost local]# cd mysql_2
[root@localhost mysql_2]# ./scripts/mysql_install_db --user=mysql --datadir=/data/mysql2
[root@localhost mysql_2]# cp /etc/my.cnf  ./my.cnf
[root@localhost mysql_2]# vim my.cnf
...
[mysqld]
port = 3306 //改为 3307
socket = /tmp/mysql.sock  //改为/tmp/mysql2.sock
//再添加一行
datadir = /data/mysql2
...
...
//启动
[root@localhost mysql_2]# cd bin/
[root@localhost bin]# ./mysqld_safe --defaults-file=../my.cnf --user=mysql &
[root@localhost bin]# echo "./mysqld_safe --defaults-file=../my.cnf --user=mysql &" >>/etc/rc.d/rc.local      //加入自动启动服务

//查看是否启动了2个MySQL
[root@localhost ~]# netstat -lnp |grep mysqld
tcp        0      0 0.0.0.0:3306                0.0.0.0:*    LISTEN      3169/mysqld
tcp        0      0 0.0.0.0:3307                0.0.0.0:*    LISTEN      3037/mysqld
unix  2      [ ACC ]     STREAM     LISTENING     29027  3037/mysqld    /tmp/mysql2.sock
unix  2      [ ACC ]     STREAM     LISTENING     29155  3169/mysqld    /tmp/mysql.sock

三、配置replication

// 3307 --主master   ，3306 --从slave

//实验： 先在master上创建库db1，并把库数据复制给slave
[root@localhost bin]# mysql -uroot -S /tmp/mysql2.sock
mysql> create database db1;
Query OK, 1 row affected (0.01 sec)

mysql> quit
Bye
//数据备份
[root@localhost bin]# mysqldump -uroot -S /tmp/mysql2.sock mysql > 123.sql
[root@localhost bin]# mysql -uroot -S /tmp/mysql2.sock db1 < 123.sql

1.设置master

[root@localhost ~]# vim /usr/local/mysql_2/my.cnf
...
[mysqld]
//查看是否有以下内容，没有则添加
server-id=1
log-bin=mysql-bin  

//以下参数可选择性使用
binlog-do-db=databasename1,databasename2  //需要复制的库名
binlog-ignore-db=databasename1,databasename2   //不需要复制的库名

[root@localhost ~]# pid=`ps uax |grep mysql2.sock |grep -v grep |awk '{print $2}'`
[root@localhost ~]# kill -0 $pid; sleep 3; kill $pid
[root@localhost ~]# cd /usr/local/mysql_2/bin/
[root@localhost bin]# ./mysqld_safe --defaults-file=../my.cnf --user=mysql &
[root@localhost ~]# mysqladmin -u root -S /tmp/mysql2.sock password '123456'
[root@localhost ~]# mysql -u root -S /tmp/mysql2.sock -p'123456'

mysql> grant replication slave on *.* to 'repl'@'127.0.0.1' identified by '123123';

mysql> flush tables with read lock;   //锁定数据库，此时不允许更改任何数据

mysql> show master status;      //查看状态，这些数据是要记录的，一会要在slave端用到

+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000006 |   474952 |              |                  |
+------------------+----------+--------------+------------------+

2.设置slave

[root@localhost ~]# vim /etc/my.cnf
...
//此id不能和master的一样
server-id = 1  //删除或改为 server-id = 2
//选择性添加
replicate-do-db=databasename1,databasename2
replicate-ignore-db=databasename1,databasename2

[root@localhost ~]# service mysqld restart
[root@localhost ~]# mysqldump -uroot -S /tmp/mysql2.sock -p123456 db1 > db1.sql
[root@localhost ~]# mysql -uroot -S /tmp/mysql.sock -pyourpassword -e "create database db1"
[root@localhost ~]# mysql -uroot -S /tmp/mysql.sock -pyourpassword db1 < db1.sql
[root@localhost ~]# mysql -uroot -S /tmp/mysql.sock -pyourpassword
mysql> slave stop;
mysql> change master to master_host='127.0.0.1', master_port=3307,
master_user='repl', master_password='123123',
master_log_file='mysql-bin.000006', master_log_pos=474952;
mysql> slave start;
mysql> quit

[root@localhost ~]# mysql -uroot -S /tmp/mysql2.sock -p123456 -e "unlock tables"
[root@localhost ~]# mysql -uroot -S /tmp/mysql.sock 

mysql> show slave statusG;
//确认以下两项参数都为YES

Slave_IO_Running: Yes
Slave_SQL_Running: Yes

3.测试主从

/*第1种测试*/
//在master上执行

[root@localhost ~]# mysql -uroot -S /tmp/mysql2.sock -p123456 -e "use db1;select count(*) from db"
+----------+
| count(*) |
+----------+
|        2 |
+----------+
[root@localhost ~]# mysql -uroot -S /tmp/mysql2.sock -p123456 -e "use db1;truncate table db"
[root@localhost ~]# mysql -uroot -S /tmp/mysql2.sock -p123456 -e "use db1;select count(*) from db"  //晴空了db1库db表的数据
+----------+
| count(*) |
+----------+
|        0 |
+----------+

//在slave上执行
//从上的表也被清空了
[root@localhost ~]# mysql -uroot -S /tmp/mysql.sock -pyourpassword -e "use db1; select count(*) from db"
+----------+
| count(*) |
+----------+
|        0 |
+----------+

/*第2种测试*/
//主上db表删除了
[root@localhost ~]# mysql -uroot -S /tmp/mysql2.sock -p123456 -e "use db1; drop table db"
//从上查看 ，表也不见了
[root@localhost ~]# mysql -uroot -S /tmp/mysql.sock -pyourpassword -e "use db1; select count(*) from db"
ERROR 1146 (42S02) at line 1: Table 'db1.db' doesn't exist

主从配置起来很简单，但是这种机制也是非常脆弱的，一旦我们不小心在从上写了数据，那么主从也就被破坏了。另外如果重启master，务必要先把slave停掉，也就是说需要在slave上去执行 slave stop 命令，然后再去重启master的mysql服务，否则很有可能就会中断了。当然重启完后，还需要把slave给开启 slave start.