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Centos6.3下mysql主从复制笔记

时间:2021-07-01 10:21:17 帮助过:33人阅读

MySQL主从复制结构是基于mysqlbin-log日志基础上,从库通过打开IO进程收到主库的bin-log日志增量信息,并保存到本地relaylog,而后再通过打开MYSQL进程从relaylog

MySQL主从复制结构是基于mysql bin-log日志基础上,从库通过打开IO进程收到主库的bin-log日志增量信息,并保存到本地relay log,而后再通过打开MYSQL进程从relay log上获取的增量信息并翻译成SQL语句后写到从数据库。

主从复制结构,实际上可以实现两个功能:

1.从库充当主库的数据库备份实例

2.读写分离,主库负责正常读写数据,从库只负责读数据

实际生产环境,虚拟主机,因为很多应用实际读数据库的次数远大于写数据库的次数,所以在项目开发初期,编写程序时做一个判断,对所有读的操作全部推到从库,若从库无法获取数据,则再向主库获取数据,从而在一定意义上实现读写分离,缓解主库的IO压力。

所以生产环境下推荐使用这种架构。


系统环境:centos6.3 x64

数据库: mysql-5.6.10


mysql master:192.168.100.90

mysql slave:192.168.100.91



一.部署环境:


1.关闭iptables和SELINUX

# service iptables stop

# setenforce 0

# vi /etc/sysconfig/selinux

---------------

SELINUX=disabled

---------------


2.安装配置mysql传送门:


二.主mysql配置:(mysql master)


修改mysql配置文件:

# vi /etc/my.cnf

添加:

-----------------

# Replication Master Server

# bin日志路径

log-bin = /usr/local/mysql/log/bin.log

# 服务器ID号

server-id = 1

# 忽略mysql系统库复制

binlog-ignore-db=mysql

binlog-ignore-db=information_schema

------------

重启服务

# service mysqld restart


登录mysql后台:

# mysql -u root -p123456

查看此刻登录账号:

> select user();


在master为slave添加同步帐号:

> grant replication slave on *.* to 'slave'@'192.168.100.91' identified by '123456';


查看创建的用户:

> select user.host from mysql.user;


查看权限:

> show grants for 'slave'@'192.168.100.91';


mysql锁表只读(其他账户登录mysql后无法进行写表操作,防止备份数据库后,主mysql表更新,导致和从数据库内容不一致)

> flush tables with read lock;


查看锁表倒计时时间:

> show variables like '%timeout%';

------------------------

....


wait_timeout | 28800

------------------------


将master的数据库表全部备份导出,并传送到slave服务器上。


# /usr/local/mysql/bin/mysqldump -u root -p123456 --opt --flush-logs --all-database > /root/allbak.sql

# cd ~

# scp allbak.sql root@192.168.100.91:/root


查看mysql偏移量(数据库如果有写操作,偏移值会递增)

# mysql -u root -p123456 -e "show master status"

----------------------

+------------+----------+--------------+------------------+-------------------+

| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |

+------------+----------+--------------+------------------+-------------------+

| bin.000009 | 120 | | | |

+------------+----------+--------------+------------------+-------------------+

----------------------

保证FILE列和Position列与从库配置一致:



三.从mysql配置(mysql slave)


修改mysql配置文件:

# vi /etc/my.cnf

添加:

--------------------

# Replication Slave Server

# bin日志路径(无需开bin-log日志)

#log-bin = /usr/local/mysql/log/bin.log

server-id=2

# 只读:

read-only

# 忽略mysql系统库复制

binlog-ignore-db=mysql

binlog-ignore-db=information_schema

---------------------


重启服务

# service mysqld restart


恢复server的数据库到slave

#/usr/local/mysql/bin/mysql -u root -p123456 < /root/allbak.sql


配置连接同步到server端:

# mysql -u root -p123456;

> stop slave;

> change master to master_host='192.168.100.90',master_user='slave',master_password='123456',master_log_file="bin.000009",master_log_pos= 120 ;

> start slave;

注:master_log_file表示从主数据库哪个bin-log文件开始同步

master_log_pos表示从该bin-log文件哪条记录点开始同步

需与主库偏移值保持同步


回到主mysql数据库解锁(mysql master)

# mysql -u root -p123456

> unlock tables;


最后登陆从mysql后台查看主从连接状态

# mysql -u root -p123456 -e "show slave status\G;"

找到这五行,如下则主从配置成功:

------------------------

Slave_IO_State: Waiting for master to send event

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

Read_Master_Log_Pos: 120

Relay_Master_Log_File: bin.000009

-------------------------


四.测试主从是否同步:

(server)

# mysql -u root -p123456 -e "create database test02;"

# mysql -u root -p123456 -e "show databases like 'test02';"

------------

+-------------------+

| Database (test02) |

+-------------------+

| test02 |

+-------------------+

------------

(cilent)

# mysql -u root -p123456 -e "show databases like 'test02';"

-------------

+-------------------+

| Database (test02) |

+-------------------+

| test02 |

+-------------------+

-------------

测试成功。。


当server端的数据库数据发生变化时,client端会同步更新,从而实现主库备份和读写分离作用。

这里注意几点:

1.mysql从库中需在my.cnf配置文件中加入 read-only参数,保证从库只读。

# echo "read-only" >> /etc/my.cnf


2.忽略从库mysql与information_schema系统表同步

# echo "binlog-ignore-db=mysql" >> /etc/my.cnf

# echo "binlog-ignore-db=information_schema" >> /etc/my.cnf


生产环境主库用户的授权,授权增删改查权限。

> GRANT SELECT,INSERT,UPDATE,DELETE ON *.* to 'user'@'%' identified by '123456';


生产环境从库的授权,仅授权查权限。

> GRANT SELECT ON *.* to 'user'@'%' identified by '123456';


3.从库默认不开启bin-log日志功能,除非做下级从库级联同步,服务器空间,才需开启从库的bin-log日志。


4.主库由于硬件故障,如何将从库提升为主库(一主多从)

(mysql slave)

(1) 确保从机没有再同步的SQL语句,即出现Has read all relay log再关闭从库IO_Threat进程

# mysql -uroot -p123456

> stop slave IO_THREAD

(2) 关闭从库slave服务,然后将其提升为主库

> stop slave

> reset master

(3) 更换从库IP为故障主库IP(配置方法略)

(4) 删除新的主库master.info和relay-log.info,防止下次重启还会按照从库启动

# cd /usr/local/mysql/log

# rm -rf master.info relay-log.info

(5) 重新配置从库连接主库的账号同步信息,以及在下级从库重新设置偏移量保持与新的主库一致即可。

最后待主库硬件恢复,将其再设置为从库并更换为上述从库IP地址,完成主从切换。


五.配置脚本:

1.如果想实现无人值守备份主数据库,可添加如下脚本,并在凌晨执行定时任务:

# vi /etc/rc.d/mysql_bak.sh

---------------------

#!/bin/sh


MYSQL_USER=root

MYSQL_PW="123456"


LOG_PATH=/usr/local/mysql/log

DATA_PATH=/usr/local/mysql/data

LOG_FILE=${LOG_PATH}/mysqllog_`date +%F`.log

DATA_FILE=${DATA_PATH}/mysql_backup_`date +%F`.sql.gz


BIN_PATH=/usr/local/mysql/bin

MYSQL_CMD="$BIN_PATH/mysql -u$MYSQL_USER -p$MYSQL_PW"

MYSQL_DUMP="$BIN_PATH/mysqldump -u$MYSQL_USER -p$MYSQL_PW --opt --flush-logs --all-database"


$MYSQL_CMD -e "flush tables with read lock;"

echo "-------show master status result-------" >> $LOG_FILE

$MYSQL_CMD -e "show master status" >> $LOG_FILE

${MYSQL_DUMP}|gzip > $DATA_FILE

$MYSQL_CMD -e "unlock tables"

mail -s "mysql slave log" 1234567@qq.com < $LOG_FILE

---------------------

凌晨3:30执行备份数据库操作:

# crontab -e

---------------------

30 3 * * * /bin/sh /etc/rc.d/mysql_bak.sh > /dev/mull 2>&1

---------------------

# service crond restart


2.如果想实现将主库备份的数据分发到从库,恢复从库数据库,以及开启从库功能,香港服务器租用,可添加如下脚本

注:这里建议主从先做好秘钥认证:

详见传送门:

# vi /etc/rc.d/mysql_bak1.sh

------------------

#!/bin/sh


MYSQL_USER=root

MYSQL_PW="123456"


MYSQL_SLAVE_IP="192.168.100.91"

SSH_PATH="/usr/bin/ssh"

SSH_CMD="${SSH_PATH} ${MYSQL_SLAVE_IP}"

GZIP_CMD="/bin/gzip"


LOG_PATH=/usr/local/mysql/log

DATA_PATH=/usr/local/mysql/data

LOG_FILE=${LOG_PATH}/mysqllog_`date +%F`.log

DATA_FILE=${DATA_PATH}/mysql_backup_`date +%F`.sql.gz


BIN_PATH=/usr/local/mysql/bin

MYSQL_CMD="$BIN_PATH/mysql -u$MYSQL_USER -p$MYSQL_PW"

MYSQL_DUMP="$BIN_PATH/mysqldump -u$MYSQL_USER -p$MYSQL_PW --opt --flush-logs --all-database"


$MYSQL_CMD -e "flush tables with read lock;"

echo "-------show master status result-------" >> $LOG_FILE

$MYSQL_CMD -e "show master status" >> $LOG_FILE

${MYSQL_DUMP}|gzip > $DATA_FILE


#config slave

cd ${DATA_PATH}

scp "mysql_backup_`date +%F`.sql.gz" $MYSQL_SLAVE_IP:/tmp/

${SSH_CMD} "${GZIP_CMD} -d /tmp/mysql_backup_`date +%F`.sql.gz"

${SSH_CMD} "${MYSQL_CMD} < /tmp/mysql_backup_`date +%F`.sql"


${SSH_CMD} "cat |$MYSQL_CMD" << EOF

stop slave;

change master to

master_host='192.168.100.90',

master_user='slave',

master_password='123456',

master_log_file="bin.000009",

master_log_pos= 120;

start slave;

EOF


$SSH_CMD $MYSQL_CMD -e "show slave status\G;"|egrep "IO_Running|SQL_Running" >> $LOG_FILE


$MYSQL_CMD -e "unlock tables"

mail -s "mysql slave log" 1234567@qq.com < $LOG_FILE

$SSH_CMD mail -s "mysql slave log" 1234567@qq.com < $LOG_FILE

------------------



-------大功告成---------


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