>>What happens when it is overloaded? You can't access the console / control panel? When it is overloaded, most of the time, I can still access the console via SSH and issue a reboot command. The system even responds by saying the system is going to reboot. But, no reboot happens. I have to ask my host company to do a manual reboot every time.
>>Simple answer is to add more RAM and / or optimize your processes. How can I optimize my processes? I have no idea although this is my third dedicated server.
It sounds weird to me that once a reboot command is given and the system receives the command, but just nothing happens. Any clue for this strange thing?
Probably is or will reboot just the system as u said is overloaded so it takes forever for the command to happen. The host is probably killing the power really not something I would want to happen very much. I would follow the above suggestions find out why this is happening and fix it asap.