转-LVS+Keepalived 介绍
作者:NetSeekhttp://www.linuxtone.org(IT运维专家网|集群架构|性能调优)
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更新时间:2008-10-27
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。
LVS+Keepalived介绍
LVS
LVS是LinuxVirtualServer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
二.网站负载均衡拓朴图
IP信息列表：
名称IP
LVS-DR-Master61.164.122.6
LVS-DR-BACKUP61.164.122.7
LVS-DR-VIP61.164.122.8
WEB1-Realserver61.164.122.9
WEB2-Realserver61.164.122.10
GateWay61.164.122.1
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三.安装LVS和Keepalvied软件包
1.下载相关软件包
#mkdir/usr/local/src/lvs
#cd/usr/local/src/lvs
#wgethttp://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz
#wgethttp://www.keepalived.org/software/keepalived-1.1.15.tar.gz
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2.安装LVS和Keepalived
#lsmod|grepip_vs
#uname-r
2.6.18-53.el5PAE
#ln-s/usr/src/kernels/2.6.18-53.el5PAE-i686//usr/src/linux
#tarzxvfipvsadm-1.24.tar.gz
#cdipvsadm-1.24
#make&&makeinstall
#find/-nameipvsadm#查看ipvsadm的位置
#tarzxvfkeepalived-1.1.15.tar.gz
#cdkeepalived-1.1.15
#./configure&&make&&makeinstall
#find/-namekeepalived#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/
#servicekeepalivedstart|stop#做成系统启动服务方便管理.
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四.配置LVS实现负载均衡
1．LVS-DR，配置LVS脚本实现负载均衡
注:此脚本在于演示方便大家理解lvs,在keepalived方案中不要启动此脚本，所以看后面有注掉，很多朋友对此有问题。关于LVS的keepalvied的HA方案，完全由keepalived.conf一个文件搞定，特此声明！
#vi/usr/local/sbin/lvs-dr.sh
#!/bin/bash
#description:startLVSofDirectorServer
#Writtenby:NetSeekhttp://www.linuxtone.org
GW=61.164.122.1
#websitedirectorvip.
SNS_VIP=61.164.122.8
SNS_RIP1=61.164.122.9
SNS_RIP2=61.164.122.10
./etc/rc.d/init.d/functions
logger$0calledwith$1
case"$1"in
start)
#setsquidvip
/sbin/ipvsadm--set30560
/sbin/ifconfigeth0:0$SNS_VIPbroadcast$SNS_VIPnetmask255.255.255.255broadcast$SNS_VIPup
/sbin/routeadd-host$SNS_VIPdeveth0:0
/sbin/ipvsadm-A-t$SNS_VIP:80-swrr-p3
/sbin/ipvsadm-a-t$SNS_VIP:80-r$SNS_RIP1:80-g-w1
/sbin/ipvsadm-a-t$SNS_VIP:80-r$SNS_RIP2:80-g-w1
touch/var/lock/subsys/ipvsadm>/dev/null2>&1
;;
stop)
/sbin/ipvsadm-C
/sbin/ipvsadm-Z
ifconfigeth0:0down
routedel$SNS_VIP
rm-rf/var/lock/subsys/ipvsadm>/dev/null2>&1
echo"ipvsadmstoped"
;;
status)
if[!-e/var/lock/subsys/ipvsadm];then
echo"ipvsadmstoped"
exit1
else
echo"ipvsadmOK"
fi
;;
*)
echo"Usage:$0{start|stop|status}"
exit1
esac
exit0
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2．配置Realserver脚本.
#vi/usr/local/sbin/realserver.sh
#!/bin/bash
#description:Configrealserverloandapplynoarp
#Writtenby:NetSeekhttp://www.linuxtone.org
SNS_VIP=61.164.122.8
./etc/rc.d/init.d/functions
case"$1"in
start)
ifconfiglo:0$SNS_VIPnetmask255.255.255.255broadcast$SNS_VIP
/sbin/routeadd-host$SNS_VIPdevlo: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/null2>&1
echo"RealServerStartOK"
;;
stop)
ifconfiglo:0down
routedel$SNS_VIP>/dev/null2>&1
echo"0">/proc/sys/net/ipv4/conf/lo/arp_ignore
echo"0">/proc/sys/net/ipv4/conf/lo/arp_announce
echo"0">/proc/sys/net/ipv4/conf/all/arp_ignore
echo"0">/proc/sys/net/ipv4/conf/all/arp_announce
echo"RealServerStoped"
;;
*)
echo"Usage:$0{start|stop}"
exit1
esac
exit0
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或者采用secondaryipaddress方式配置
#vi/etc/sysctl.conf
net.ipv4.conf.lo.arp_ignore=1
net.ipv4.conf.lo.arp_announce=2
net.ipv4.conf.all.arp_ignore=1
net.ipv4.conf.all.arp_announce=2
#sysctl?p
#ipaddradd61.164.122.8/32devlo
#ipaddlist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:
#watchipvsadm?ln
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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
!ConfigurationFileforkeepalived
global_defs{
notification_email{
}
smtp_server127.0.0.1
#smtp_connect_timeout30
router_idLVS_DEVEL
}
#20081013writtenby:netseek
#VIP1
vrrp_instanceVI_1{
stateMASTER#备份服务器上将MASTER改为BACKUP
interfaceeth0
virtual_router_id51
priority100#备份服务上将100改为99
advert_int1
authentication{
auth_typePASS
auth_pass1111
}
virtual_ipaddress{
61.164.122.8
#(如果有多个VIP，继续换行填写.)
}
}
virtual_server61.164.122.880{
delay_loop6#(每隔10秒查询realserver状态)
lb_algowrr#(lvs算法)
lb_kindDR#(DirectRoute)
persistence_timeout60#(同一IP的连接60秒内被分配到同一台realserver)
protocolTCP#(用TCP协议检查realserver状态)
real_server61.164.122.980{
weight3#(权重)
TCP_CHECK{
connect_timeout10#(10秒无响应超时)
nb_get_retry3
delay_before_retry3
connect_port80
}
}
real_server61.164.122.1080{
weight3
TCP_CHECK{
connect_timeout10
nb_get_retry3
delay_before_retry3
connect_port80
}
}
}
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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.停掉lvs_dr.sh演示脚本
vi/etc/rc.local
#/usr/local/sbin/lvs-dr.sh将lvs-dr.sh这个脚本注释掉。
#/usr/local/sbin/lvs-dr.shstop停止lvs-dr脚本
#/etc/init.d/keepalivedstart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.
整个LVS负均衡HA方案，由keepalived.conf一个文件即可搞定！
4.查看lvs服务是否正常
#watchipvsadm?ln
IPVirtualServerversion1.2.1(size=4096)
ProtLocalAddressortSchedulerFlags
->RemoteAddressortForwardWeightActiveConnInActConn
TCP61.164.122.8:80wrrpersistent60
->61.164.122.10:80Route300
->61.164.122.9:80Route300
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#tail?f/var/log/message监听日志，查看状态，测试LVS负载均衡及高可用性是否有效。
5．停Master服务器的keepalived服务，查看BAKCUP服务器是否能正常接管服务。
四．相关参考
1．LVS基础知识汇总
LVS的算法介绍http://bbs.linuxtone.org/viewthread.php?tid=69
学习LVS的三种转发模式http://bbs.linuxtone.org/viewthread.php?tid=77
LVS中的IP负载均衡技术http://bbs.linuxtone.org/viewthread.php?tid=68
更多的请到http://www.linuxtone.org负载均衡版查看
Keepalived相关参考资料。
http://www.keepalived.org/documentation.html
提供DOC文档下载:
PDF下载：http://docs.linuxtone.org/ebooks/load%20balance/lvs/