mysql基于keepalived的双主热备(HA)

应用场景:

网站流量不高，压力不大，但是对服务器的可靠性要求极其高，例如实时在线OA系统，政府部门网站系统，医院实时报医系统，公安局在线报案系统，股市后台网站系统等等，他们的压力不是很大，但是对可靠性要求是非常高的.

特性:

通过vip飘移，实现故障切换。只能支持2个节点，不支持更多节点管理；容易发生脑裂.

优点:

数据同步非常简单，不像负载均衡对数据一致性要求非常高，实现起来相对复杂维护也颇为不便，双机热备用rsync就可以实现了操作和维护非常简单.

缺点:

脑裂无法解决，需要引入第三方仲裁节点，有一个节点空闲.

前提:

存在互为主从的mysql实例(A:192.168.255.134 B:192.168.255.135)

A实例:192.168.255.134

1.首先安装keepalived

a.源码安装

b.yum安装(yum install keepalived -y)

2.安装MySQL-python(检测mysql是否启动是基于python的)

yum install MySQL-python

3.修改keepalived.conf(/etc/keepalived/keepalived.conf)

vrrp_script vs_mysql_134 {

script "/home/keepalived/checkMySQL.py -h 192.168.255.134 -P 3306" //监控脚本

interval 60 // 监控时间

}

vrrp_instance VI_134 {

state BACKUP

nopreempt

interface eth0 //绑定虚拟IP的网络接口

virtual_router_id 134 //VRRP组名，两个节点的设置必须一样，以指明各个节点属于同一VRRP组

priority 100

advert_int 5

authentication {

auth_type PASS // 加密

auth_pass 1111 // 加密的密码，两台服务器一定要一样，不然会出错

}

track_script {

vs_mysql_134 // 执行监控的服务

}

virtual_ipaddress {

192.168.255.150 //VIP 地址

}

}

4.创建/home/keepalived/checkMySQL.py文件，内容如下：

#!/usr/bin/python

#coding: utf-8

#

import sys

import os

import getopt

import MySQLdb

import logging

dbhost='localhost'

dbport=3306

dbuser='monitor'

dbpassword='m0n1tor'

def checkMySQL():

global dbhost

global dbport

global dbuser

global dbpassword

shortargs='h:P:'

opts, args=getopt.getopt(sys.argv[1:],shortargs)

for opt, value in opts:

if opt=='-h':

dbhost=value

elif opt=='-P':

dbport=value

#print "host : %s, port: %d, user: %s, password: %s" % (dbhost, int(dbport), dbuser, dbpassword)

db = instanceMySQL(dbhost, dbport, dbuser, dbpassword)

st = db.ishaveMySQL()

#if ( db.connect() != 0 ):

# return 1

#db.disconnect()

return st

class instanceMySQL:

conn = None

def __init__(self, host=None,port=None, user=None, passwd=None):

self.dbhost= host

self.dbport = int(port)

self.dbuser = user

self.dbpassword = passwd

def ishaveMySQL(self):

cmd="ps -ef | egrep -i \"mysqld\" | egrep -iv \"mysqld_safe\" | grep -v grep | wc -l"

mysqldNum = os.popen(cmd).read()

cmd ="netstat -tunlp | grep \":%s\" | wc -l" % self.dbport

mysqlPortNum= os.popen(cmd).read()

#print mysqldNum, mysqlPortNum

if ( int(mysqldNum) <= 0):

print "error"

return 1

if ( int(mysqldNum) > 0 and mysqlPortNum <= 0):

return 1

return 0

def connect(self):

# print "in db conn"

# print "host : %s, port: %d, user: %s, password: %s" % (self.dbhost, self.dbport, self.dbuser, self.dbpassword)

try:

self.conn=MySQLdb.connect(host="%s"%self.dbhost, port=self.dbport,user="%s"%dbuser, passwd="%s"%self.dbpassword)

except Exception, e:

# print " Error"

print e

return 1

return 0

def disconnect(self):

if (self.conn):

self.conn.close()

self.conn = None

if __name__== "__main__":

st=checkMySQL()

sys.exit(st)

5. 将步骤4中创建的文件赋予可自行的权限

chmod 755 /home/keepalived/checkMySQL.py

6.在mysql创建一个监控用户：

GRANT REPLICATION CLIENT ON *.* TO 'monitor'@'%' IDENTIFIED BY 'm0n1tor';

7.启动keepalived，提示如下(tail -f /var/log/messages):



则表示成功。

B实例:192.168.255.135

1.同实例A

2.同实例A

3.修改keepalived.conf(/etc/keepalived/keepalived.conf)

vrrp_script vs_mysql_135 {

script "/home/keepalived/checkMySQL.py -h 192.168.255.135 -P 3306"

interval 60

}

vrrp_instance VI_135 {

state BACKUP

nopreempt

interface eth0

virtual_router_id 134

priority 100

advert_int 5

authentication {

auth_type PASS

auth_pass 1111

}

track_script {

vs_mysql_135

}

virtual_ipaddress {

192.168.255.150

}

}

4.同实例A

5.同实例A

6.同实例A

7.启动keepalived，提示如下(tail -f /var/log/messages):



则表示成功