基础知识：
需求：
最初只有主数据库，这样即使有数据备份，对业务保证也不够高（业务不大，不需要做主主）。所以新增一台数据库备用服务器，做主从复制。
准备：
在master数据库服务器的操作
添加用于复制的用户
添加用于复制的用户
grant replication client,replication slave on *.* to 'angus'@'%.%.%.%' identified by 'password';
修改server id （只要主从server id不一样就行，可以再从服务器该。）
开启binary logging（一般都开启过）
修改server id
开启relay-log
开启binary logging（主从切换 做准备）
操作：
1，在从服务器上配置好数据库，最后和主数据库是一个版本。
1，在从服务器上配置好数据库，最后和主数据库是一个版本。
2，sed -i '/^server-id/s#1#2#g' /etc/my.cnf
3，开启relay-log 在/etc/my.cnf 的[mysqld]区域添加下面代码
relay-log=relay-bin
relay-log=relay-bin.index
relay-log=relay-bin.index
sed -i '/^server-id/a\relay-log=relay-bin\nrelay-log=relay-bin.index' /etc/my.cnf
4，对主数据进行一次完全备份
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.1.66 Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> flush tables with read lock;
Query OK, 0 rows affected (0.02 sec)
mysql> quit
Bye
[root@localhost ~]# mysqldump -hlocalhost -uroot -p --all-databases --single-transaction --master-data=2 > /root/all.sql
Enter password:
[root@localhost ~]# ls
all.sql anaconda-ks.cfg install.log install.log.syslog Music Pictures Public Templates Videos yum.sh
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.1.66-log Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)
mysql> quit
Bye
[root@localhost ~]#
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.1.66 Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> flush tables with read lock;
Query OK, 0 rows affected (0.02 sec)
mysql> quit
Bye
[root@localhost ~]# mysqldump -hlocalhost -uroot -p --all-databases --single-transaction --master-data=2 > /root/all.sql
Enter password:
[root@localhost ~]# ls
all.sql anaconda-ks.cfg install.log install.log.syslog Music Pictures Public Templates Videos yum.sh
[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.1.66-log Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> unlock tables;
Query OK, 0 rows affected (0.00 sec)
mysql> quit
Bye
[root@localhost ~]#
把all.sql 传送到从服务器上，并导入到mysql服务器上。
[root@localhost ~]# /etc/init.d/mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
[root@localhost ~]# mysql < all.sql
[root@localhost ~]# /etc/init.d/mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
[root@localhost ~]# mysql < all.sql
[root@localhost ~]# /etc/init.d/mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
[root@localhost ~]# mysql -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.1.61-log Source distribution
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.1.61-log Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| info.angus.com |
| know.angus.com |
| mysql |
| test |
+--------------------+
7 rows in set (0.02 sec)
+--------------------+
| Database |
+--------------------+
| information_schema |
| info.angus.com |
| know.angus.com |
| mysql |
| test |
+--------------------+
7 rows in set (0.02 sec)
设置从数据库复制数据的主数据（MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=342这些内容可以在less all.sql中找到-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=106;）
mysql> change master to master_host='x.x.x.x',master_user='angus',master_password='password',MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=342;
Query OK, 0 rows affected (0.03 sec)
mysql> START SLAVE;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW SLAVE STATUS\G
Query OK, 0 rows affected (0.03 sec)
mysql> START SLAVE;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW SLAVE STATUS\G
如果没有报错，此时主从复制基本上都成功了。
主从切换：
由于各种原因，住数据库挂了，并且段时间内无法修复，为了不影响，线上服务，需要及时做主从切换。
[root@localhost ~]# mysql -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.1.61-log Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> STOP SLAVE IO_THREAD; //确保从服务器已经处理了中继日志中的所有语句
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW PROCESSLIST; //检查SHOW PROCESSLIST语句的输出，直到你看到Has read all relay log
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------+------------------+
| 5 | system user | | NULL | Connect | 2349 | Has read all relay log; waiting for the slave I/O thread to update it | NULL |
| 8 | root | localhost | NULL | Query | 0 | NULL | SHOW PROCESSLIST |
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)
mysql> STOP SLAVE;
Query OK, 0 rows affected (0.00 sec)
mysql> RESET MASTER;
Query OK, 0 rows affected (0.08 sec)
mysql> RESET SLAVE;
Query OK, 0 rows affected (0.01 sec)
mysql> quit
Bye
[root@localhost ~]# /etc/init.d/mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.1.61-log Source distribution
Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> STOP SLAVE IO_THREAD; //确保从服务器已经处理了中继日志中的所有语句
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW PROCESSLIST; //检查SHOW PROCESSLIST语句的输出，直到你看到Has read all relay log
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------+------------------+
| 5 | system user | | NULL | Connect | 2349 | Has read all relay log; waiting for the slave I/O thread to update it | NULL |
| 8 | root | localhost | NULL | Query | 0 | NULL | SHOW PROCESSLIST |
+----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)
mysql> STOP SLAVE;
Query OK, 0 rows affected (0.00 sec)
mysql> RESET MASTER;
Query OK, 0 rows affected (0.08 sec)
mysql> RESET SLAVE;
Query OK, 0 rows affected (0.01 sec)
mysql> quit
Bye
[root@localhost ~]# /etc/init.d/mysqld restart
Stopping mysqld: [ OK ]
Starting mysqld: [ OK ]
此时 从服务器升级为主服务器，一般情况下从服务的性能没有主服务器的好，所以当主服务器正常后，首先进入服务找到故障前一刻master状态。
mysql> show master status;
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000002 | 106 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.01 sec)
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000002 | 106 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.01 sec)
然后让原来的主服务器做从服务器（开启中继日志），复制数据（首先的有执行复制权限的用户如angus1）
mysql> change master to master_host='x.x.x.x',master_user='angus1',master_password='password',MASTER_LOG_FILE='mysql-bin.000002 , MASTER_LOG_POS=106;
Query OK, 0 rows affected (0.03 sec)
Query OK, 0 rows affected (0.03 sec)
等所有数据复制完成后，再做次主从切换。
附：
mysql对数据库过滤：有两种形式，一般使用下面一种。
mysql对数据库过滤：有两种形式，一般使用下面一种。
复制过滤器
binlog-do-db = mydb 表示只限制与mydb的修改操作才会记录到二进制日志
binlog-inore-db = mydb
中继日志 过滤
replicate-do-db = mydb
replicate-ignore-db = mydb
replicate-do-table = table
replicate-ignore-table = table
replicate-wild-do-table = db_pattern.tb1_pattern
replicate-wild-ignore-table = db_pattern.tb1_pattern
binlog-do-db = mydb 表示只限制与mydb的修改操作才会记录到二进制日志
binlog-inore-db = mydb
中继日志 过滤
replicate-do-db = mydb
replicate-ignore-db = mydb
replicate-do-table = table
replicate-ignore-table = table
replicate-wild-do-table = db_pattern.tb1_pattern
replicate-wild-ignore-table = db_pattern.tb1_pattern