This document discusses using LVS (Linux Virtual Server) and Keepalived to implement high performance and high availability load balancing. It provides instructions on installing LVS and Keepalived, configuring LVS for load balancing, and using Keepalived to realize load balancing and high availability. Key aspects covered include using LVS-DR and real server scripts, and configuring Keepalived on the master and backup servers.

1. 利用 LVS+Keepalived 实现高性能高可用负载均衡
ByPat博客专注于linux资源分享 http://blog.bypat.com
作者：Redhat
日期:20 -1-27
背景:
随着你的网站业务量的增长你网站的服务器压力越来越大？需要负载均衡方案！ 商
业的硬件如 F5 又太贵，你们又是创业型互联公司如何有效节约成本，节省不必要的浪费？
同时实现商业硬件一样的高性能高可用的功能？有什么好的负载均衡可伸张可扩展的方案
吗？答案是肯定的！有！我们利用 LVS+Keepalived 基于完整开源软件的架构可以为你提供
一个负载均衡及高可用的服务器。
一． LVS+Keepalived 介绍
1. 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） ；
八种调度算法（rr,wrr,lc,wlc,lblc,lblcr,dh,sh）。
2. Keepalvied
Keepali ved 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
二. 网站负载均衡拓朴图
.
IP 信息列表：
名称 IP
L VS-DR-Master 61.164.122.6
L VS-DR-BACKUP 61.164.122.7
L VS-DR-VIP 61.164.122.8
WEB1-R ealserver 61.164.122.9
WEB2-R ealserver 61.164.122.10
G ateWay 61.164.122.1

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三. 安装 LVS 和 Keepalvied 软件包
1. 下载相关软件包
#m kdir /usr/local/src/lvs
#c d /usr/local/src/lvs
#w get http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
#w get http://www.keepalived.org/software/keepalived-1.1.15.tar.gz
2. 安装 LVS 和 Keepalived
#lsm od |grep ip_vs
#uname -r
2.6.18-53.el5PAE
#ln -s /usr/src/kernels/2.6.18-53.el5PAE-i686/ /usr/src/linux
#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.
四. 配置 LVS 实现负载均衡
1． LV S-DR，配置 LVS 脚本实现负载均衡
#vi /usr/local/sbin/lvs-dr.sh
#!/bin/bash
# description: start LVS of DirectorServer
GW=61.164.122.1
# website director vip.
SNS_VIP=61.164.122.8
SNS_RIP1=61.164.122.9
SNS_RIP2=61.164.122.10

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./e tc/rc.d/init.d/functions
logger $0 called with $1
case "$1" in
start)
# set squid vip
/ sbin/ipvsadm --set 30 5 60
/ sbin/ifconfig eth0:0 $SNS_VIP broadcast $SNS_VIP netmask 255.255.255.255
broadcast $SNS_VIP up
/ sbin/route add -host $SNS_VIP dev eth0:0
/ sbin/ipvsadm -A -t $SNS_VIP:80 -s wrr -p 3
/ sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP1:80 -g -w 1
/ sbin/ipvsadm -a -t $SNS_VIP:80 -r $SNS_RIP2:80 -g -w 1
t ouch /var/lock/subsys/ipvsadm >/dev/null 2>&1
;;
stop)
/sbin/ipvsadm -C
/sbin/ipvsadm -Z
i fconfig eth0:0 down
i fconfig eth0:1 down
rout e del $SNS_VIP
route del $SS_VIP
rm -rf /var/lock/subsys/ipvsadm >/dev/null 2>&1
ech o "ipvsadm stoped"
;;
status)
i f [ ! -e /var/lock/subsys/ipvsadm ];then
echo "ipvsadm stoped"
exit 1
else
echo "ipvsadm OK"
fi
;;
*)
echo "Usage: $0 {start|stop|status}"
exit 1
esac

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exit 0
2． 配置 Realserver 脚本.
#vi /usr/local/sbin/realserver.sh
#!/bin/bash
# description: Config realserver lo and apply noarp
SNS_VIP=61.164.122.8
. /etc/rc.d/init.d/functions
case "$1" in
start)
ifco nfig lo:0 $SNS_VIP netmask 255.255.255.255 broadcast $SNS_VIP
/sbin/route add -host $SNS_VIP dev lo:0
ec ho "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
ec ho "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
ec ho "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
ec ho "2" >/proc/sys/net/ipv4/conf/all/arp_announce
sy sctl -p >/dev/null 2>&1
ec ho "RealServer Start OK"
;;
stop)
i fconfig lo:0 down
rou te del $SNS_VIP >/dev/null 2>&1
ec ho "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore
ec ho "0" >/proc/sys/net/ipv4/conf/lo/arp_announce
ec ho "0" >/proc/sys/net/ipv4/conf/all/arp_ignore
ec ho "0" >/proc/sys/net/ipv4/conf/all/arp_announce
ec ho "RealServer Stoped"
;;
*)
ec ho "Usage: $0 {start|stop}"
exit 1
esac
exit 0
或者采用 secondary ip address 方式配置
# vi /etc/sysctl.conf
net.ipv4.conf.lo.arp_ignore = 1
net.ipv4.conf.lo.arp_announce = 2

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net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_announce = 2
#sysctl –p
#ip addr add 61.164.122.8/32 dev lo
#ip add list 查看是否绑定
3. 启动 lvs-dr 脚本和 realserver 启本，在 DR 上可以查看 LVS 当前状态:
#watch ipvsadm –ln
五．利用 Keepalvied 实现负载均衡和和高可用性
1.配置在主负载均衡服务器上配置 keepalived.conf
#vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
n otification_email {
cnseek@gmail.com
# fai lover@firewall.loc
# sy sadmin@firewall.loc
}
n otification_email_from sns-lvs@gmail.com
sm tp_server 127.0.0.1
# smtp_connect_timeout 30
ro uter_id LVS_DEVEL
}
# VIP1
vrrp_instance VI_1 {
state MASTER #备份服务器上将 MASTER 改为 BACKUP
i nterface eth0
virtual_router_id 51
priority 100 # 备份服务上将 100 改为 99
ad vert_int 1
au thentication {
auth_type PASS
a uth_pass 1111
}
virtual_ipaddress {
61. 164.122.8
#(如果有多个 VIP，继续换行填写.)
}
}
virtual_server 61.164.122.8 80 {

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delay_loop 6 #(每隔 10 秒查询 realserver 状态)
lb_algo wrr #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 60 #(同一 IP 的连接 60 秒内被分配到同一台 realserver)
protocol TCP #(用 TCP 协议检查 realserver 状态)
rea l_server 61.164.122.9 80 {
weight 3 #(权重)
TCP_CHECK {
connect_timeout 10 #(10 秒无响应超时)
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
rea l_server 61.164.122.10 80 {
weight 3
TCP_CHECK {
c onnect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
2. BACKUP 服 务 器 同 上 配 置 ， 先 安 装 lvs 再 按 装 keepalived, 仍 后 配 置
/etc/keepalived/keepalived.conf，只需将红色标示的部分改一下即可.
3. vi /etc/rc.local
# /usr/local/sbin/lvs-dr.sh 将 lvs-dr.sh 这个脚本注释掉。步
# /usr/local/sbin/lvs-dr.sh stop 停止 lvs-dr 脚本
#/ etc/init.d/keepalived start 启动 keepalived 服务，keepalived 就能利用 keepalived.conf 配
置文件，实现负载均衡和高可用.
4. 查看 lvs 服务是否正常
#watch ipvsadm –ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port F orward Weight ActiveConn InActConn
TCP 61.164.122.8:80 wrr persistent 60
-> 61.164.122.10:80 Route 3 0 0
-> 61.164.122.9:80 Route 3 0 0

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#t ail –f /var/log/message 监听日志，查看状态。
5．停 Master 服务器的 keepalived 服务，查看 BAKCUP 服务器是否能正常接管.
四．相关参考
Keepalived 相关参考资料。
http://www.keepalived.org/documentation.html