前言* 随着互联网飞速的发展，互联网WEB服务器，必须要保证每天7x24x365不间断服务，随着人数不断的增加，有什么好的WEB前端架构呢？既能实现高可用、负载均衡、成本有最低廉呢？答案有木有呢？LVS+Keepalived是一个非常不错的前端均衡选择。（今天来研究一下如何快速配置LVS及日常的维护，供参考！）
一、系统环境
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LVS-Master
192.168
.
2.108
LVS-BACKUP
192.168
.
2.109
LVS-DR-VIP
192.168
.
2.100
WEB1-Realserver
192.168
.
2.79
WEB2-Realserver
192.168
.
2.80
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二、Keepalived安装
由于我们使用的是lvs+keepalived，所以这里不需要配置lvs-dr脚本，直接在keepalived.conf里面配置即可！
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#!/bin/sh
###脚本编写目的:自动安装lvs+keepalived
###编写时间:
2011
年
7
月
6
日
17
:
25
:
39
###初稿人:wugk
###定义变量
DIR1=/usr/src
DIR2=/usr/local
cat << EOF
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++Welcome to
use
Linux installed a key LVS+KEEPALIVED shells scripts
+++++++++++++++++++++*************************++++++++++++++++++++++++
EOF
if
[ $UID -ne
0
];then
echo “This script must
use
root user ,please exit……”
sleep
2
exit
0
fi
download ()
{
cd $DIR1 && wget -c http:
//www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.24.tar.gz http://www.keepalived.org/software/keepalived-1.1.15.tar.gz
if
[ $? =
0
];then
echo
"Download LVS Code is OK!"
else
echo
"Download LVS Code is failed,Please check!"
exit
1
fi
}
ipvsadm_install ()
{
ln -s $DIR1/kernels/
2.6
.* $DIR1/linux
cd $DIR1 && tar xzvf ipvsadm-
1.24
.tar.gz &&cd ipvsadm-
1.24
&& make && make install
if
[ $? -eq
0
];then
echo
"Install ipvsadm success,please waiting install keepalived ..............."
else
echo
"Install ipvsadm failed ,please check !"
exit
1
fi
}
keepalived_install ()
{
cd $DIR1 && tar -xzvf keepalived-
1.1
.
15
.tar.gz &&cd keepalived-
1.1
.
15
&& ./configure && make && make install
if
[ $? -eq
0
];then
echo
"Install keepalived success,please waiting configure keepalived ..............."
else
echo
"Install keepalived failed ,please check install version !"
exit
1
fi
}
######如果以上软件包编译报错的话，请检查相关的版本跟系统版本之间的关系，然后手动下载安装.
keepalived_config ()
{
cp $DIR2/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/ && cp $DIR2/etc/sysconfig/keepalived /etc/sysconfig/ && mkdir -p /etc/keepalived &&cp $DIR2/etc/keepalived/keepalived.conf /etc/keepalived/ && cp $DIR2/sbin/keepalived /usr/sbin/
if
[ $? -eq
0
];then
echo
"Keepalived system server config success!"
else
echo
"Keepalived system server config failed ,please check keepalived!"
exit
1
fi
}
PS3=
"Please select Install Linux Packages:"
select option
in
download ipvsadm_install keepalived_install keepalived_config
do
$option
done
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以上脚本分别在lvs-master和lvs-backup上执行安装。
三、Keepalived配置
也可以参考配置：
http://chinaapp.sinaapp.com/download/keepalived.conf
可以直接打开
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! Configuration Filefor keepalived
global_defs {
notification_email {
wgkgood@
163
.com
}
notification_email_from wgkgood@
163
.com
smtp_server
127.0
.
0.1
smtp_connect_timeout
30
router_id LVS_DEVEL
}
# VIP1
vrrp_instance VI_1 {
state MASTER
interface
eth0
lvs_sync_daemon_inteface eth0
virtual_router_id
51
priority
100
advert_int
5
authentication {
auth_type PASS
auth_pass
1111
}
virtual_ipaddress {
192.168
.
2.100
}
}
#REAL_SERVER_1
virtual_server
192.168
.
2.100
80
{
delay_loop
6
lb_algo wlc
lb_kind DR
persistence_timeout
60
protocol TCP
real_server
192.168
.
2.79
80
{
weight
100
TCP_CHECK {
connect_timeout
10
nb_get_retry
3
delay_before_retry
3
connect_port
80
}
}
#REAL_SERVER_2
real_server
192.168
.
2.80
80
{
weight
100
TCP_CHECK {
connect_timeout
10
nb_get_retry
3
delay_before_retry
3
connect_port
80
}
}
}
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注意***Lvs-backup端同样配置，只需要更改state MASTER为state BACKUP，修改priority 100为priority 90即可。
四、WEB服务端配置
如下的VIP1指的是lvs-dr-vip地址，及对外提供访问的虚拟ip：
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#!/bin/sh
PS3=
"Please Choose whether or not to start a realserver VIP1 configuration:"
select i
in
"start"
"stop"
do
case
"$i"
in
start)
read -p
"Please enter the virtual server IP address:"
VIP1
ifconfig lo:
0
$VIP1 netmask
255.255
.
255.255
broadcast $VIP1
/sbin/route add -host $VIP1 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
2
>&
1
echo
"RealServer Start OK"
exit
0
;;
stop)
ifconfig lo:
0
down
route del $VIP1 >/dev/
null
2
>&
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
"RealServer Stoped"
exit
1
;;
*)
echo
"Usage: $0 {start|stop}"
exit
2
esac
done
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脚本会提示是否启动，按1即启动，然后输入vip地址 192.168.2.100 ，用ifconfig你会看到：lo:0的ip即表示配置ip成功。
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lo:
0
Link encap:Local Loopback
inet addr:
192.168
.
2.100
Mask:
255.255
.
255.255
UP LOOPBACK RUNNING MTU:
16436
Metric:
1
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五、测试LVS+keepalived
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/etc/init.d/keepalived restart 查看lvs-master日志：
在浏览器里面访问 http:
//192.168.2.100/ 即可！当你宕掉lvs-master后，lvs-backup会接管变成lvs-master提供服务，当lvs-master故障恢复后，lvs-backup又会变成原来的状态！
所安装的脚本可以在这里下载：
在lvs-master和lvs-backup上执行http:
//chinaapp.sinaapp.com/download/lvs-keepalived.sh
在web服务器端执行http:
//chinaapp.sinaapp.com/download/realserver.sh
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六、实战建议
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为了解决脑裂问题，需要把主MASTER和备BACKUP各自的keepalived.conf配置文件里面的state 状态都改成BACKUP，优先级分别设置
100
和
90
。
我们常听说脑裂问题，到底什么是脑裂问题呢？
在集群配置中的split-brain现象是指，主从之间互相检测不到心跳，同时抢占资源，导致
服务无法正常访问的情况。所以我们还需要在主备keepalived.conf添加nopreempt 指令！
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附realserver.sh脚本文件：
本文转自 wgkgood 51CTO博客，原文链接:http://blog.51cto.com/wgkgood/605322
