Keepalived 是一个基于VRRP协议来实现的LVS服务高可用方案，可以利用其来避免单点故障。一个mysql或lvs或nginx服务会有2台服务器运行Keepalived，一台为主服务器（MASTER），一台为备份服务器（BACKUP），但是对外表现为一个虚拟IP，主服务器会发送特定的消息给备份服务器，当备份服务器收不到这个消息的时候，即主服务器宕机的时候，备份服务器就会接管虚拟IP，继续提供服务，从而保证了高可用性。
以下简图为例，当服务调用mysql的时候，直接调用vip，这样即使master上宕机，依旧可访问从数据库。
Keepalive的安装：
1、 安装环境包
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[root@jacken ~]
# yum -y install kernel-devel openssl-devel popt-devel
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2、 安装keepalive
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[root@jacken ~]
# wget http://www.keepalived.org/software/keepalived-1.1.15.tar.gz
[root@jacken ~]
# tar -zxf keepalived-1.1.15.tar.gz
[root@jacken ~]
# cd keepalived-1.1.15
[root@jacken keepalived-1.1.15]
#./configure --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/
[root@jacken ~]
# make && make install
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在编译选项中，“--sysconf”指定了Keepalived配置文件的安装路径.“--with-kernel-dir”是个很重要的参数，但这个参数并不是要把Keepalived编译进内核，而是指定使用内核源码中的头文件，即include目录。只有在使用LVS时，才需要用到“--with-kernel-dir”参数，其他时候是不需要的。
3、 设置keepalive
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[root@jacken ~]
# DIR=/usr/local/ ; cp$DIR/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
[root@jacken ~]
# cp $DIR/etc/sysconfig/keepalived /etc/sysconfig/ && mkdir -p /etc/keepalived
[root@jacken ~]
# cp $DIR/sbin/keepalived /usr/sbin/
[root@jacken ~]
# cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
[root@jacken ~]
# /etc/init.d/keepalivedrestart
Stopping keepalived: [FAILED]
Starting keepalived: [ OK ]
[root@jacken ~]
#modprobe ip_vs
[root@jacken ~]
#modprobe ip_vs_rr
[root@jacken ~]
#modprobe ip_vs_wrr
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Other
脚本配置文件：
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[root@jacken ~]
# chmod +xinstall_keepalive.sh
[root@jacken ~]
# cat install_keepalive.sh
#!/bin/bash
yum -y
install
kernel-devel openssl-devel popt-devel &&
wget http:
//www
.keepalived.org
/software/keepalived-1
.1.15.
tar
.gz &&
tar
-zxf keepalived-1.1.15.
tar
.gz &&
cd
keepalived-1.1.15 &&
.
/configure
--with-kernel-
dir
=
/usr/src/kernels/2
.6.32-431.el6.x86_64/ &&
make
&&
make
install
&&
DIR=
/usr/local/
cp
$DIR
/etc/rc
.d
/init
.d
/keepalived
/etc/rc
.d
/init
.d/ &&
cp
$DIR
/etc/sysconfig/keepalived
/etc/sysconfig/
&&
mkdir
-p
/etc/keepalived
&&
cp
$DIR
/sbin/keepalived
/usr/sbin/
&&
cp
/usr/local/etc/keepalived/keepalived
.conf
/etc/keepalived/
&&
/etc/init
.d
/keepalived
restart
if
[ $? -
eq
0 ];
then
echo
-e
'\e[32mInstall Keepalive Successfully!\e[0m'
else
echo
-e
'\e[31mInstall Keepalive Failure!\e[0m'
fi
[root@jacken ~]
#
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其实这个不算是什么脚本，方便安装而已，一定要注意内核版本号要对应。
本文转自Jacken_yang 51CTO博客，原文链接：http://blog.51cto.com/linuxnote/1652612，如需转载请自行联系原作者
