What's the fastest way to kill a server? [closed]

Question

For the heck of it, what's the fastest way to kill a server, other than just pulling the plug?

Kill as in a(n) (un)safe shutdown, you could theoretically reboot it and have it survive the incident.

Edit: Tangentially related to serverfault.com, my apologies. IMHO, the question is related in that these are possible things users could be attempting, as well as in the case of adverse conditions there might be reasons server admins want to take down multiple boxes lest undefined "damage" might occur.

Edit2: opened to community wiki.

Answer 1

On a Sun server, Stop-A suspends the kernel immediately. You can press the key combination or send an equivalent signal on the serial console.

On Linux, Alt-SysRq-O crashes the kernel immediately. Through a remote shell, you can do echo o > /proc/sysrq-trigger. There are other magic SysRq keys that will cause an immediate unclean reboot. Alt-SysRq-S is handy to sync to disk first.

Answer 2

give an oracle dba the root password.

Answer 3

C4, or other explosive

Answer 4

For Windows, this one is simply delicious:

http://msdn.microsoft.com/en-us/library/ff545499(v=VS.85).aspx

Just a little Registry edit, and you'll be able to trigger an instant BSOD on any Windows system by pressing CTRL + SCROLL LOCK twice.

Answer 5

You're not scaling. If it doesn't scale, it's not a solution.

EMP pulse.

Theoretically, if it didn't hard-fry the electronics, you could reinstall the OS and things would survive the incident. Fastest way to turn off an entire datacenter of machines -- just use a larger pulse -- and will work better than just pulling the power, as those UPSes/batteries won't get in your way.

Of course, it's not ideal scaling, as you're dealing inverse-square law for power vs coverage area and any decent computer scientist will wince at such an O constraint and look for a better algorithm. Perhaps a bunch of EMP pulse emitters, each triggerable by being subjected to a pulse, would give you an easy scaling cascade system, at the cost of small delays in the effect as the pulses ripple out.

Answer 6

Universal: Find a paperclip and jam it in the "Reset" hole

Answer 7

Run a fork bomb as root? (or any user if no user resource limits are in place)

Or cat hair, dust, and other general household detritus gumming up all the cooling fans?

Answer 8

This is handy for shutting down a Windows computer remotely:

C:\WINDOWS\system32\shutdown.exe -r -m \\MYCOMPUTERNAME01
C:\WINDOWS\system32\shutdown.exe -r -m \\192.168.1.186

-r means you are completely shutting it down and rebooting
-m means it's a remote machine

Answer 9

For Windows:

shutdown -s -f -t 0 \\ServerName

This forces an immediate shutdown and causes all the applications to close (whether they'd like to or not).

Answer 10

shutdown -t now has always been fast enough for me

Answer 11

Depending on your system

halt --force

might get the job done (as far as quickness goes).

Answer 12

Cross the pins in a USB port with something metal (paper clip works well), and you'll have a really quick power down (ie, instant). I've only ever seen this happen in a laptop, but I'd imagine it'd happen on a desktop as well. Amazingly, the computer has booted back up normally after it was done.

Answer 13

Two fun ones that may not give you 'comes back up' (data corruption is vicious):

dd if=/dev/zero of=/dev/mem
dd if=/dev/urandom of=/dev/kmem

Of course, the other way around would be interesting too.