安装keepalived

keepalived：http://www.keepalived.org/index.html

引用

它是一个基于VRRP协议来实现的WEB服务高可用方案，可以利用其来避免单点故障。一个WEB服务至少会有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。（摘）

1.安装ipvsadm
yum -y install ipvsadm
或者

wget http://www.linuxvirtualserver.org/software/kernel-2.6/ipvsadm-1.26.tar.gz
tar -zxvf ipvsadm-1.26.tar.gz
cd ipvsadm-1.26
make&&make install

错误处理一：

In file included from libipvs.h:13,
                 from libipvs.c:23:
ip_vs.h:15:29: error: netlink/netlink.h: No such file or directory
ip_vs.h:16:31: error: netlink/genl/genl.h: No such file or directory
ip_vs.h:17:31: error: netlink/genl/ctrl.h: No such file or directory

这个需要安装 libnl-devel 包， yum install libnl-devel 就可以了。
错误处理二：

ipvsadm.o: In function `parse_options':
/ipvsadm-1.26/ipvsadm.c:432: undefined reference to `poptGetContext'
/ipvsadm-1.26/ipvsadm.c:435: undefined reference to `poptGetNextOpt'
/ipvsadm-1.26/ipvsadm.c:660: undefined reference to `poptBadOption'
/ipvsadm-1.26/ipvsadm.c:502: undefined reference to `poptGetNextOpt'
/ipvsadm-1.26/ipvsadm.c:667: undefined reference to `poptStrerror'
/ipvsadm-1.26/ipvsadm.c:667: undefined reference to `poptBadOption'
/ipvsadm-1.26/ipvsadm.c:670: undefined reference to `poptFreeContext'
/ipvsadm-1.26/ipvsadm.c:677: undefined reference to `poptGetArg'
/ipvsadm-1.26/ipvsadm.c:678: undefined reference to `poptGetArg'
/ipvsadm-1.26/ipvsadm.c:679: undefined reference to `poptGetArg'
/ipvsadm-1.26/ipvsadm.c:690: undefined reference to `poptGetArg'
/ipvsadm-1.26/ipvsadm.c:693: undefined reference to `poptFreeContext'

安装popt-static：yum install popt-static
重新make&&make install安装成功。

2.安装keepalived

wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz
tar –zxvf keepalived-1.2.7.tar.gz
cd keepalived-1.2.7
./configure
make && make install

错误处理一：

configure: error: 
  !!! OpenSSL is not properly installed on your system. !!!
  !!! Can not include OpenSSL headers files.            !!!

需要安装opendevel：yum -y install openssl-devel
重新make&&make install安装成功。

3.配置为服务
cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /usr/local/sbin/keepalived /usr/sbin/
可以这样启动/停止：
service keepalived start|stop
设为开机启动：
chkconfig keepalived on