Keepalived 实现双机热备

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原理

首先有一个虚拟 ip 暴露给客户端，虚拟 ip 对应的 mac 地址为一台真实服务器，即用户向虚拟 ip 发送一个请求，该请求会被分发到真实服务器上。

现在有 2 台真实服务器，一台 master，一台 backup，master 和 backup 上都运行着 keepalived，当 master 挂了的时候，backup 检测之后，自己成为 master, 且 arp 缓存虚拟 ip 对应的 mac 地址将变为 backup 的 mac 地址，这样请求虚拟 ip 的报文会被发送到 backup

架构图如下：

Keepalived 实现双机热备

安装

主机：192.168.1.227

备机：192.168.1.246

虚拟 ip：192.168.1.99

安装命令：

wget http://www.keepalived.org/software/keepalived-1.2.13.tar.gz
tar -zxvf keepalived-1.2.13.tar.gz
cd keepalived-1.2.13
./configure –disable-fwmark –prefix=/usr/local/keepalived
make && make install

整理：

mkdir /etc/keepalived/
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
ln -s /usr/local/keepalived/sbin/keepalived /sbin/

配置：

vi /etc/keepalived/keepalived.conf

Master

! Configuration File for keepalived

global_defs {
notification_email {
acassen@firewall.loc
failover@firewall.loc
sysadmin@firewall.loc
}
notification_email_from Alexandre.Cassen@firewall.loc
smtp_server 192.168.200.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}

vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.99
}
}

Backup 和 master 一样，只要修改如下地方：

vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 99 # 这里改为 99，master 优先级是 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.99
}
}

管理命令：

停止
service keepalived stop
启动
service keepalived start
重启
service keepalived restart
查看状态
service keepalived status

测试

在本机上查看虚拟 ip 状态

ip add

Keepalived 实现双机热备

在同一网段的其他机器上查询 arp 缓存

arp -a

Keepalived 实现双机热备

这里的 1.99 对应的 mac 地址是 1.227

停掉 master 的 keepalived

service keepalived stop