mysql主备复制搭建(使用mysqld_muti)

这里我使用单台服务器上的两个mysql实例进行搭建，主要用到了mysql自带的mysqld_multi

一、复制原理

开始搭建前有个mysql复制原理的基础知识需要补充:

mysql进行主备复制使用到了三个线程：

1.主库上的转存储线程:

会将mysql server提交的事务写入到二进制文件中，这个二进制文件就叫做binlog。

2.备库上的连接线程：

备库启动后，负责和主库通信，读取binlog，同时，将binlog存储进自己的一个叫中继日志的relaylog中。

3.备库上的relaylog重放线程:

此线程会将relaylog中的事件在备库上进行回放，说白点就是重新执行一次

二、搭建步骤

1./etc新增文件mysqld_multi.cnf

将/user/share/mysql/my-innodb-heavy-4G.cnf文件复制到/etc，重新命名为xxx.cnf（任何你想要的名字）

在配置文件中新增三个实例

[mysqld3307]
port = 3307
pid-file = /var/lib/mysql3307/mysql3307.pid
socket = /var/lib/mysql3307/mysql3307.sock
datadir=/var/lib/mysql3307
user=mysql
set-variable=max_connections=27000
log_bin = mysql-bin
server_id = 3307

[mysqld3308]
port = 3308
pid-file = /var/lib/mysql3308/mysql3308.pid
socket = /var/lib/mysql3308/mysql3308.sock
datadir=/var/lib/mysql3308
user=mysql
set-variable=max_connections=28000
log_bin = mysql-bin
server_id = 3308
relay_log = /var/lib/mysql3308/mysql-relay-bin
log_slave_updates = 1
read_only = 1

[mysqld3309]
port = 3309
pid-file = /var/lib/mysql3309/mysql3309.pid
socket = /var/lib/mysql3309/mysql3309.sock
datadir=/var/lib/mysql3309
user=mysql
set-variable=max_connections=29000
log_bin = mysql-bin
server_id = 3309
relay_log = /var/lib/mysql3309/mysql-relay-bin
log_slave_updates = 1
read_only = 1

2.做好了配置之后开启两个实例：

mysqld_multi --defaults-file=/etc/mysql/mysqld_muti.cnf start

3.开启复制前主库的准备工作:

1.在主库上增加一个复制账号：

使用sock文件登陆mysql:

mysql -uroot -p -S /var/lib/mysql3307/mysql3307.sock（这个套接字文件还记得吗，是在之前定义实例的时候定义的）

mysql>flush privileges;

登陆到备库：

mysql -uroot -p -S /var/lib/mysql3308/mysql3308.sock

1. change master to master_host = "localhost",
2. master_user = ‘replication‘,
3. master_password = ‘replication‘,（你之前在主库上创建复制账号时指定的）
4. master_port = 3306;

start slave;

查看复制是否开始工作:

5.进行正常主从测试：

在mysql3308数据库停止复制

mysql> show slave status \G;           
*************************** 1. row ***************************
               Slave_IO_State:
                  Master_Host: localhost
                  Master_User: replication
                  Master_Port: 3307
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 408
               Relay_Log_File: mysql-relay-bin.000012
                Relay_Log_Pos: 553
        Relay_Master_Log_File: mysql-bin.000005

mysql> show slave status \G;
*************************** 1. row ***************************
               Slave_IO_State:
                  Master_Host: localhost
                  Master_User: replication
                  Master_Port: 3307
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000006
          Read_Master_Log_Pos: 316

150510  1:35:41 [Note] Error reading relay log event: slave SQL thread was killed
150510  1:35:41 [Note] Slave I/O thread killed while reading event
150510  1:35:41 [Note] Slave I/O thread exiting, read up to log ‘mysql-bin.000006‘, position 316

150510  1:43:04 [Note] Slave SQL thread initialized, starting replication in log ‘mysql-bin.000006‘ at position 316, relay log ‘/var/lib/mysql3309/mysql-relay-bin.000015‘ position: 461
150510  1:43:04 [Note] Slave I/O thread: connected to master ‘[email protected]:3307‘,replication started in log ‘mysql-bin.000006‘ at position 316

6.进行异常测试：

停掉从库mysql3308和mysql3309的复制，并对主库进行日志清除操作：

delete from sky where id=‘2000‘;

purge binary logs to ‘mysql-bin.000010‘;

只能停止从数据库,然后重新在从数据库中CHANGE MASTER TO 开始,指向正确的二进制文件及偏移量