Sometimes, reboot or shutdown -r now, don’t work anymore. That really sucks, especially if you have no access to the server room or you just don’t want to get up.
But there might be another solution if you compiled your Kernel with CONFIG_MAGIC_SYSRQ: “sysrq-trigger”. If so, you have the possibility so send some, let’s say binding, commands:
Reset your server (like pressing the hardware reset button):
# echo b > /proc/sysrq-trigger
But, it might be a good idea to sync the hard disks before:
# echo s > /proc/sysrq-trigger
If you like to know more about that, try http://en.wikipedia.org/wiki/Magic_SysRq_key
One thing that might be worth to point out is how to prevent this behaviour: http://en.wikipedia.org/wiki/Magic_SysRq_key#Disabling_SysRq_key