MySQL主备复制搭建（使用mysqld_multi）

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--------------------------------------------------------------------------------
[mysqld_multi]
mysqld = /usr/bin/mysqld_safe
mysqladmin = /usr/bin/mysqladmin
user = multi_admin
password = multipass
log = /var/log/mysqld_multi.log[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--------------------------------------------------------------------------------
这里我会将将mysqld3307这个实例做为主库，mysqld3308和mysql3309这个实例作为备库

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>grant replication slave,replication client on *.* to replication@"localhost" identified by "replication"; mysql>flush privileges;--------------------------------------------------------------------------------
查看主库上的binlog是否开启:--------------------------------------------------------------------------------mysql> show master status;
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000001 | 1001 | | |
+------------------+----------+--------------+------------------+
1 row in set （0.00 sec）--------------------------------------------------------------------------------

4.开启复制:
登陆到备库：
mysql -uroot -p -S /var/lib/mysql3308/mysql3308.sock
--------------------------------------------------------------------------------change master to master_host = "localhost", master_user = "replication", master_password = "replication",（你之前在主库上创建复制账号时指定的） master_port = 3306;
start slave;
查看复制是否开始工作:--------------------------------------------------------------------------------
mysql> show slave status G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: localhost
Master_User: replication
Master_Port: 3307
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 622
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 767
Relay_Master_Log_File: mysql-bin.000001
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: 622
Relay_Log_Space: 922
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:
1 row in set （0.00 sec）--------------------------------------------------------------------------------
当看到Slave_IO_Running: Yes 和 Slave_SQL_Running: Yes证明io通信线程和sql回放线程都已经启动。至此，主备复制结构配置完成
5.进行正常主从测试：
在mysql3308数据库停止复制--------------------------------------------------------------------------------
mysql> stop slave;
Query OK, 0 rows affected （0.00 sec）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--------------------------------------------------------------------------------
在mysql3309数据库停止复制--------------------------------------------------------------------------------
mysql> stop slave;
Query OK, 0 rows affected （0.00 sec）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--------------------------------------------------------------------------------
查看mysql日志情况：--------------------------------------------------------------------------------
150510 1:33:39 [Note] Error reading relay log event: slave SQL thread was killed
150510 1:33:39 [Note] Slave I/O thread killed while reading event
150510 1:33:39 [Note] Slave I/O thread exiting, read up to log "mysql-bin.000005", position 408
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--------------------------------------------------------------------------------
在这期间，主库mysql3307进行了flush logs操作，重新生成了mysql-bin日志，并对表进行添加，删除操作。然后启动从库的复制，进行查看。--------------------------------------------------------------------------------150510 1:42:48 [Note] Slave SQL thread initialized, starting replication in log "mysql-bin.000005" at position 408, relay log "/var/lib/mysql3308/mysql-relay-bin.000012" position: 553
150510 1:42:48 [Note] Slave I/O thread: connected to master "replication@localhost:3307",replication started in log "mysql-bin.000005" at position 408
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 "replication@localhost:3307",replication started in log "mysql-bin.000006" at position 316--------------------------------------------------------------------------------
说明：从库从停止的时间点重新补回了停止期间的所有数据。
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：--------------------------------------------------------------------------------
flush logs
delete from sky where id="2000";
purge binary logs to "mysql-bin.000010";--------------------------------------------------------------------------------
然后重新启动从库的复制，日志进行报错，数据丢失，主从失败。--------------------------------------------------------------------------------
150510 1:50:53 [ERROR] Slave I/O: Got fatal error 1236 from master when reading data from binary log: "Could not find first log file name in binary log index file", Error_code: 1236
--------------------------------------------------------------------------------
解决方法：
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--------------------------------------------------------------------------------
change master to master_log_file="mysql-bin.000001",master_log_pos=106;--------------------------------------------------------------------------------
之后的数据会恢复正常主从同步。--------------------------------------分割线 --------------------------------------MySQL5.7.3.0安装配置图解教程 http://www.linuxidc.com/Linux/2014-10/108397.htmUbuntu 14.04下安装MySQL http://www.linuxidc.com/Linux/2014-05/102366.htm《MySQL权威指南（原书第2版）》清晰中文扫描版 PDF http://www.linuxidc.com/Linux/2014-03/98821.htmUbuntu 14.04 LTS 安装 LNMP NginxPHP5 （PHP-FPM）MySQL http://www.linuxidc.com/Linux/2014-05/102351.htmUbuntu 14.04下搭建MySQL主从服务器 http://www.linuxidc.com/Linux/2014-05/101599.htmUbuntu 12.04 LTS 构建高可用分布式 MySQL 集群 http://www.linuxidc.com/Linux/2013-11/93019.htmUbuntu 12.04下源代码安装MySQL5.6以及Python-MySQLdb http://www.linuxidc.com/Linux/2013-08/89270.htmMySQL-5.5.38通用二进制安装 http://www.linuxidc.com/Linux/2014-07/104509.htm--------------------------------------分割线 --------------------------------------本文永久更新链接地址