LVS+Keepalived负载均衡主备
LVS+Keepalived 介绍LVS
LVS是Linux Virtual Server的简写，意即Linux虚拟服务器，是一个虚拟的服务器集群系统。本项目在1998年5月由章文嵩博士成立，是中国国内最早出现的自由软件项目之一。目前有三种IP负载均衡技术（VS/NAT、VS/TUN和VS/DR）；
十种调度算法（rrr|wrr|lc|wlc|lblc|lblcr|dh|sh|sed|nq）。
Keepalvied
Keepalived在这里主要用作RealServer的健康状态检查以及LoadBalance主机和BackUP主机之间failover的实现
一、LVS+Keepalived负载均衡主备架构
I. 网站负载均衡拓朴图
(略)
IP信息清单：
名称 IP
[*] LVS-DR-Master 192.168.2.98
[*] LVS-DR-Backup 192.168.2.99
[*] LVS-DR-VIP 192.168.2.100
[*] Realserver01 192.168.2.101
[*] Realserver02 192.168.2.102
[*] Realserver03 192.168.2.103
[*] Realserver04 192.168.2.104
II.安装ipvsadm和keepalived软件包
ipvsadm： http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
keepalived：http://www.keepalived.org/software/keepalived-1.1.15.tar.gz
下载后建议统一放置在/usr/local/src/lvs
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#uname -r
2.6.18-53.el5PAE //查看内核版本
#ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686//usr/src/linux//防止报错
#tar zxvf ipvsadm-1.24.tar.gz
#cd ipvsadm-1.24
#make && make install
#find / -name ipvsadm# 查看ipvsadm的位置
#tar zxvf keepalived-1.1.15.tar.gz
#cd keepalived-1.1.15
#./configure&& make && make install
#find / -name keepalived# 查看keepalived位置
#cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
#cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
#mkdir /etc/keepalived
#cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
#cp /usr/local/sbin/keepalived /usr/sbin/
#service keepalived start|stop #做成系统启动服务方便管理.
III. 配置Realserver脚本
在4台Realserver主机上建立如下脚本，然后执行
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#!/bin/bash
VIP=192.168.2.100
/etc/rc.d/init.d/functions
case “$1″ in
start)
ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP up
/sbin/route add -host $VIP dev lo:0
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
sysctl -p >/dev/null
echo "RealServer Start OK"
;;
stop)
ifconfig lo:0 down
route del $VIP 2>/dev/null
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
echo "RealServer Stoped"
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
IV. 配置keepalived实现负载均衡和和高可用性
1.在LVS-DR-Master主机上编辑keepalived的配置文件 ： vim /etc/keepalived/keepalived.conf
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! Configuration File for keepalived
global_defs {
notification_email {
//此处填写你的邮件地址 }
notification_email_from your email!
smtp_server smtp.**.com
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_instance VI_1 {
state MASTER
interface eth0
lvs_sync_daemon_inteface eth0 //如是同一个网卡，可省略
virtual_router_id 77 //标识ID，请务必保证内网唯一性，和备机必须一致！
priority 100 //权重需比备机高
advert_int 2 //主备检测间隔
authentication { //主备通信密码，必须一致
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.2.100 VIP，多个请换行填写
}
}
virtual_server 192.168.2.100 80 {
delay_loop 6 //每隔6秒检测Realserver健康状况
lb_algo wlc //wlc算法,其他算法请参考ipvsadm十大算法
lb_kind DR // 采用DR模式，即直接路由，其他还有TUN和NAT两种模式。
persistence_timeout 1800 //设置超时未半小时
protocol TCP
real_server 192.168.2.101 80 { //第一个realserver，请注意80和后面{之间有个空格！
weight 100 //权重
HTTP_GET { //通过检测网页来检查Realserver健康状态
url {
path /XX/index.jsp //Realserver上的网页，如/model/index.jsp
status_code 200 //正确的返回值，一般是200
}
connect_timeout 3 //超时3秒，则失败
nb_get_retry 3 //失败重试次数
delay_before_retry 3 //重试间隔时间
}
}
real_server 192.168.2.102 80 {
weight 100
TCP_CHECK { //此范例为TCP检查方法，区别于HTTP方法，推荐使用HTTP方法。
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
real_server 192.168.2.103 80 {
weight 100
HTTP_GET {
url {
path /XX/index.jsp
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
real_server 192.168.2.104 80 {
weight 100
HTTP_GET {
url {
path /XX/index.jsp
status_code 200
}
connect_timeout 3
nb_get_retry 3
delay_before_retry 3
}
}
2.编辑LVS-DR-Backup上的keepalived配置文件(可拷贝Master上的)，然后如下修改：
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state BACKUP //主机上则为Master
priority 90 //权值小于主机
其余保持不变即可。
V. 启动LVS
Realserver脚本启动之后不需要操作，然后依次启动LVS主机上的keepalived服务即可： service keepalived start
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