Mysql Replication 主从同步

Posted 2020-08-03 小怪兽的技术博客

简介：

mysql 的主从同步功能，这种解决方案是企业很常见的一种。常用于备份数据库，当客户端操作主库时，主库会产生binlog日志文件，
从库通过复制主库的binlog日志文件，然后解析成相应的 SQL 语句在从库执行，实现主从一致的效果。
这种解决方案只提供了日志的同步执行功能，而从库只能提供读操作，当主服务器发生故障时，必须手动处理故障转移，一般情况下的做法是将一台从服务器改为主服务器。

Master : 192.168.1.88
Slave : 192.168.1.80

一、配置 Master

[[email protected] ~]# vim /etc/my.cnf

log-bin = mysql-bin # 开启 binlog 日志记录
server-id = 1 # 设置 id 号，此 ID 号全局唯一

[[email protected] ~]# service mysqld start

[[email protected] ~]# netstat -anpt | grep 3306 # 检测 Mysql 是否启动成功

[[email protected] ~]# chkconfig --add mysqld
[[email protected] ~]# chkconfig --level 35 mysqld on

[[email protected] ~]# iptables -I INPUT -s 192.168.1.80 -p tcp --dport 3306 -j ACCEPT

[[email protected] ~]# service iptables save

二、配置 Slave

[[email protected] ~]# vim /etc/my.cnf

server-id = 2                           # 设置 id 号，此 ID 号全局唯一
relay-log = mysql-relay-bin             # 指定 relay-log 日志文件的命名格式
replicate-wild-ignore-table = mysql.%   # 过滤不需要复制的表
replicate-wild-ignore-table = test.%
replicate-wild-ignore-table = information_schema.%
replicate-wild-ignore-table = performance_schema.%

[[email protected] ~]# service mysqld start

[[email protected] ~]# chkconfig --add mysqld
[[email protected] ~]# chkconfig --level 35 mysqld on

[[email protected] ~]# iptables -I INPUT -s 192.168.1.88 -p tcp --dport 3306 -j ACCEPT

[[email protected] ~]# service iptables save

三、小插曲

四、Master 创建复制用户并授权

[[email protected] ~]# mysql -u root -p123456

mysql> grant replication slave on *.* to ‘rep1_user‘@‘192.168.1.80‘ identified by ‘rep1_passwd‘;

mysql> show master status;
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000008 | 324 | | |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

五、Slave 添加 Master 信息

[[email protected] ~]# mysql -u root -p123456

mysql> change master to -> master_host=‘192.168.1.88‘,
-> master_user=‘rep1_user‘,
-> master_password=‘rep1_passwd‘,
-> master_log_file=‘mysql-bin.000008‘,
-> master_log_pos=324;

mysql> start slave;

mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.88
Master_User: rep1_user
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000008
Read_Master_Log_Pos: 324
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 267
Relay_Master_Log_File: mysql-bin.000008
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: mysql.%,test.%,information_schema.%,performance_schema.%
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 324
Relay_Log_Space: 430
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: b5e20203-86b5-11e4-b69c-000c29d099fa
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:
1 row in set (0.00 sec)

## 重点关注：Slave_IO_Running 跟 Slave_SQL_Running 这两个主从复制线程，正常情况下这两项都为 YES ！

## 还需要关注：Slave_IO_State、Master_Host、Master_Log_File、Read_Master_Log_Pos、Relay_Log_File、Relay_Log_Pos、Relay_Master_Log_File

## Replicate_Wild_Ignore_Table 这项可以看到同步过程中过滤了哪些库（表）。

附：

三、小插曲

## 在做主从同步前，主库已经有数据时，需要做以下处理。

mysql> flush tables with read lock;   # 主库锁表操作，让数据库只能读，不能写

## 保留此终端，重新打开一个 tty ，如果关闭此终端则锁表失效。

[[email protected] ~]# cd /usr/local/

[[email protected] local]# tar zcf mysql.tar.gz mysql   # 备份整个数据库

[[email protected] local]# rsync -a mysql.tar.gz 192.168.1.80:/usr/local/   # 将数据传到从库

[[email protected] local]# service mysqld stop     # 关闭从库的 Mysql

[[email protected] local]# mv mysql old.mysql      # 将原有 mysql 目录改名

[[email protected] local]# tar zxf mysql.tar.gz    # 解压出主库的 mysql 目录

[[email protected] local]# service mysqld restart # 重启主库 Mysql 服务

[[email protected] local]# service mysqld start    # 启动从库 Mysql 服务