keepalived从机接管后主机恢复不抢占VIP

在lvs+keepalived环境中，为了减小keepalived主从切换带来的意外风险，，设置主机恢复后不抢占VIP。
待进行vrrp协议通告备机不可用时切换。主要修改两个地方。（红色部分）

只需修改主服务器state MASTER改为state BACKUP并添加nopreempt

! Configuration File for keepalived

global_defs {
notification_email {
[e-mail]
}
notification_email_from [e-mail]
smtp_server localhost
smtp_connect_timeout 30
router_id mfs_master
}

vrrp_instance VI_1 {
state BACKUP
interface eth1
virtual_router_id 51
priority 100
nopreempt
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.0.11
}
}