mysql主从配置小记：
共有四台机器：A(10.1.10.28),B(10.1.10.29),C(10.1.10.30),D(10.1.10.31)。
配置后结果：A-C互为主从，B为A的slave，D为C的slave。
0)准备工作
在四台机器上面安装好mysql后，创建用于同步的账号。
添加账户：
INSERT INTO user (Host,User, Password,Select_priv,Insert_priv,Update_priv,Delete_priv, Create_priv,Drop_priv) VALUES('%','test',password('test'),'Y','Y','Y','Y','Y','Y');
刷新数据库：
FLUSH PRIVILEGES;
1)配置A-C互为主从
修改A配置文件为：
server-id = 1 replicate-do-db=test replicate-do-db=test_admin log-bin=mysql-bin log-slave-updates replicate-wild-do-table=test.% replicate-wild-do-table=test_admin.% binlog-ignore-db=mysql slave-skip-errors=all
修改C配置文件为：
server-id = 3 binlog-do-db=test binlog-do-db=test_admin log-bin=mysql-bin log-slave-updates replicate-wild-do-table=test.% replicate-wild-do-table=test_admin.% binlog-ignore-db=mysql slave-skip-errors=all
重启mysql是配置生效
将A设置为主：
停止同步：
slave stop;
清空服务器master日志：
reset master;
授权同步账号：
GRANT REPLICATION SLAVE ON *.* TO 'test'@'%' IDENTIFIED BY 'test'；
刷新授权:
flush privileges;
锁定数据库:
flush tables with read lock;
将C设置为从：
停止同步：
slave stop;
配置同步信息：
CHANGE MASTER TO MASTER_HOST='10.1.10.28', MASTER_USER='test', MASTER_PASSWORD='test', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=107;
将C设置为主：
停止同步：
slave stop;
清空服务器master日志：
reset master;
授权同步账号：
GRANT REPLICATION SLAVE ON *.* TO 'test'@'%' IDENTIFIED BY 'test'；
刷新授权:
flush privileges;
锁定数据库:
flush tables with read lock;
将A设置为从：
停止同步：
slave stop;
配置同步信息：
CHANGE MASTER TO MASTER_HOST='10.1.10.30', MASTER_USER='test', MASTER_PASSWORD='test', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=107;
2)将B设置为A的从
server-id = 2 replicate-do-db=test replicate-do-db=test_admin log-bin=mysql-bin log-slave-updates replicate-wild-do-table=test.% replicate-wild-do-table=test_admin.% binlog-ignore-db=mysql slave-skip-errors=all
重启mysql服务
停止同步：
slave stop;
配置同步信息：
CHANGE MASTER TO MASTER_HOST='10.1.10.28', MASTER_USER='test', MASTER_PASSWORD='test', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=107;
启动同步:
slave start;
3)将D设置为C的从
server-id = 4 replicate-do-db=test replicate-do-db=test_admin log-bin=mysql-bin log-slave-updates replicate-wild-do-table=test.% replicate-wild-do-table=test_admin.% binlog-ignore-db=mysql slave-skip-errors=all
重启mysql服务
停止同步：
slave stop;
配置同步信息：
CHANGE MASTER TO MASTER_HOST='10.1.10.30', MASTER_USER='test', MASTER_PASSWORD='test', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=107;
启动同步:
slave start;
完成之后可以创建添加数据测试一下是否可以。
下面是常见错误处理：
1）
change master导致的：
Last_IO_Error: error connecting to master 'repl1@IP:3306' - retry-time: 60 retries
2）
在没有解锁的情况下停止slave进程：
mysql> stop slave;
ERROR 1192 (HY000): Can't execute the given command because you have active locked tables or an active transaction
3）
change master语法错误，落下逗号
mysql> change master to
-> master_host='IP'
-> master_user='USER',
-> master_password='PASSWD',
-> master_log_file='mysql-bin.000002',
-> master_log_pos=106;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'master_user='USER',
master_password='PASSWD',
master_log_file='mysql-bin.000002' at line 3
4）
在没有停止slave进程的情况下change master
mysql> change master to master_host=‘IP', master_user='USER', master_password='PASSWD', master_log_file='mysql-bin.000001',master_log_pos=106;
ERROR 1198 (HY000): This operation cannot be performed with a running slave; run STOP SLAVE first
5）
A B的server-id相同：
Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server ids;
these ids must be different for replication to work (or the --replicate-same-server-id option must be used on
slave but this does not always make sense; please check the manual before using it).
查看server-id
mysql> show variables like 'server_id';
手动修改server-id
mysql> set global server_id=2; #此处的数值和my.cnf里设置的一样就行
mysql> slave start;
6）change master之后，查看slave的状态，发现slave_IO_running 为NO