I usually reboot but it's not possible in production level servers
But it is possible to drop to single user mode? That doesn't add up. You may as well just reboot as the machine's services are down in single user mode anyway. If you're worried about your "uptime", forget it. Nobody cares about uptimes of a single machine. It's the services you provide that are important, not an individual server. If you make sure your services are still available (by using HA or standby systems) then it really doesn't matter if you reboot the machine dozens of times as your services would still be available.I usually reboot but it's not possible in production level servers