Linux负载均衡(4)-Linux Keepalived 实现双机热备

试用Keepalived来做双机热备，服务器信息如下：

服务器1：Centos / 192.168.18.20 [IP] / 192.168.18.22 [虚拟IP]

服务器2：Centos / 192.168.18.21 [IP] / 192.168.18.22 [虚拟IP]

1. 安装Keepalived

2台Server都使用下面的命令安装Keepalived：

yum install keepalived -y

2. Server1 Keepalived 配置

$ vi /etc/keepalived/keepalived.conf

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100                   # 优先级
    advert_int 1                 # 心跳间隔(秒)
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.18.22         # 虚拟IP
    }
}

3. Server2 Keepalived 配置

$ vi /etc/keepalived/keepalived.conf

vrrp_instance VI_1 {
    state BACKUP              # 备份机
    interface eth0
    virtual_router_id 51
    priority 99                   # 优先级，比主服务器底
    advert_int 1                 # 心跳间隔(秒)
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.18.22         # 虚拟IP
    }
}

4. 启动Keepalived

$ service keepalived start

启动keepalived后，可看到2台Server都绑定了虚拟IP：

$ ip a

# Server 1:
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:24:8c:8c:67:43 brd ff:ff:ff:ff:ff:ff
    inet 192.168.18.20/24 brd 192.168.18.255 scope global eth0
    inet 192.168.18.22/32 scope global eth0
    inet6 fe80::224:8cff:fe8c:6743/64 scope link 
       valid_lft forever preferred_lft forever

# Server 2:
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:23:54:bf:ab:17 brd ff:ff:ff:ff:ff:ff
    inet 192.168.18.21/24 brd 192.168.18.255 scope global eth0
    inet 192.168.18.22/32 scope global eth0
    inet6 fe80::223:54ff:febf:ab17/64 scope link 
       valid_lft forever preferred_lft forever

5. 测试

浏览器访问http://192.168.18.22，出现 This is Server 1.

将192.168.18.20关闭，再访问http://192.168.18.22，出现This is Server 2.