Holding down the power button when the systems freezes

[Jorge Martínez López]

2013/1/29 Sam Varshavchik <mrsam at courier-mta.com>:
>
> When the machine freezes, try pressing Alt-SysRq-b to force a reboot, if the
> kernel is still alive, somewhere. This will still require a filesystem
> repair, but at least it'll save wear/tear on the hard drives.
>

Even better is to use Alt + SysRq + REISUB (sequentially)

R = unRaw      (take control of keyboard back from X),
E =  tErminate (send SIGTERM to all processes, allowing them to
terminate gracefully),
I =  kIll      (send SIGKILL to all processes, forcing them to
terminate immediately),
S =  Sync     (flush data to disk),
U =  Unmount  (remount all filesystems read-only),
B= reBoot.

http://en.wikipedia.org/wiki/Magic_SysRq_key

Greetings,
--
Jorge Martínez López <jorgeml at gmail.com> http://www.jorgeml.net