mysql设置主从的重要性和必要性不必多说，下面开始详细说明如何搭建主从。
1、主服务器上创建一个用于复制的账户。
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.168.47.3' IDENTIFILED BY '1234'; mysql> flush privileges;
2、主服务器参数修改
[root@localhost ~]# vi /usr/local/mysql5.6/etc/my.cnf 修改如下内容 server-id = 1 log-bin=mysql-bin
3、主服务器备份数据，并传输
mysql> flush tables with read lock; mysql> show master status; +------------------+----------+--------------+------------------+-------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------------+----------+--------------+------------------+-------------------+ | mysql-bin.000036 | 3252 | | | | +------------------+----------+--------------+------------------+-------------------+ 1 row in set (0.00 sec)
[root@localhost ~]# /usr/local/mysql5.6/bin/./mysqldump -uroot -p --all-databases | gzip > bak.sql.gz [root@localhost ~]# scp bak.sql.gz root@192.168.47.3:~/
mysql> unlock tables;
4、从服务器恢复数据
[root@localhost bin]# gunzip bak.sql.gz [root@localhost bin]# mysql -uroot -p mysql> source ~/bak.sql;
5、修改从服务器配置
[root@localhost bin]# vi /etc/my.cnf 添加如下内容 server-id = 2
重启服务器
[root@localhost ~]# service mysql restar
6、从服务器设置主从配置
mysql> CHANGE MASTER TO
-> MASTER_HOST='192.168.47.5',
-> MASTER_USER='repl',
-> MASTER_PASSWORD='1234',
-> MASTER_LOG_FILE='mysql-bin.000036',
-> MASTER_PORT=3307,
-> MASTER_LOG_POS=3252;
MASTER_HOST指的是主服务器的IP地址，
MASTER_USER指的是复制的账户
MASTER_PASSWORD指的是账户的密码
MASTER_PORT指的是主服务器端口
MASTER_LOG_FILE指的是bin-log的文件
MASTER_LOG_POS指的是日志文件位
7、从服务器启动slave线程
mysql> start slave; mysql> show processlist; +----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------------+------------------+-----------+---------------+ | Id | User | Host | db | Command | Time | State | Info | Rows_sent | Rows_examined | +----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------------+------------------+-----------+---------------+ | 1 | system user | | NULL | Connect | 714 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL | 0 | 0 | | 2 | system user | | NULL | Connect | 714 | Waiting for master to send event | NULL | 0 | 0 | | 4 | root | localhost | NULL | Query | 0 | init | show processlist | 0 | 0 | +----+-------------+-----------+------+---------+------+-----------------------------------------------------------------------------+------------------+-----------+---------------+ 3 rows in set (0.08 sec)
这已经表明主从已经搭建成功。
8、测试
主服务器中
mysql> use warehouse Database changed mysql> select * from aaa; +------+------+ | a | b | +------+------+ | 1 | 2 | | 1 | 2 | | 1 | 2 | | 2 | 3 | | 2 | 7 | +------+------+ 5 rows in set (0.06 sec)
从服务器中
mysql> use warehouse; Database changed mysql> select * from aaa; +------+------+ | a | b | +------+------+ | 1 | 2 | | 1 | 2 | | 1 | 2 | | 2 | 3 | | 2 | 7 | +------+------+ 5 rows in set (0.21 sec)
主服务器中
mysql> insert into aaa values (5,7),(56,21); Query OK, 2 rows affected (0.21 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select * from aaa; +------+------+ | a | b | +------+------+ | 1 | 2 | | 1 | 2 | | 1 | 2 | | 2 | 3 | | 2 | 7 | | 5 | 7 | | 56 | 21 | +------+------+ 7 rows in set (0.00 sec)
从服务器中
mysql> select * from aaa; +------+------+ | a | b | +------+------+ | 1 | 2 | | 1 | 2 | | 1 | 2 | | 2 | 3 | | 2 | 7 | | 5 | 7 | | 56 | 21 | +------+------+ 7 rows in set (0.00 sec)
9、管理主从
查看从服务器状态
mysql> show slave status G; *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: 192.168.47.5 Master_User: repl Master_Port: 3307 Connect_Retry: 60 Master_Log_File: mysql-bin.000036 Read_Master_Log_Pos: 3484 Relay_Log_File: localhost-relay-bin.000002 Relay_Log_Pos: 283 Relay_Master_Log_File: mysql-bin.000036 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: 3484 Relay_Log_Space: 460 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: Replicate_Ignore_Server_Ids: Master_Server_Id: 1 Master_UUID: 86d34969-fa5d-11e6-b372-000c29c88c3f Master_Info_File: /usr/local/mysql/data/master.info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: Executed_Gtid_Set: Auto_Position: 0 1 row in set (0.00 sec)
关心的两个信息是Slave_IO_Running和Slave_SQL_Running是否是YES。Slave_IO_Running是从主服务器读取BINLOG日志，并写入到从服务器的中继日志中；Slave_SQL_Running负责读取和执行中继日志信息。
注意：如果需要从服务器禁止写入操作，则需要更改参数read-only，使从服务器非root账户只能读数据。