Kill a hanged disk i/o process...

[Modulok]

To the best of my knowledge, most processes can be killed explicitly
by "kill -s KILL;" There are a few which cannot, such as disk i/o
processes. The idea here is data integrity.

On the rare occasion however, (when attempting to recover data from
corrupt disks for example), I've had a process invoked by the "cp"
command, hang. This poses a significant problem as these processes are
disk i/o processes, and as such cannot be terminated (even by root).
So, other than physically hitting the reset button on the case, is
there a more eloquent method of forcefully halting a hanged disk i/o
process? The idea of "you don't want to terminate a disk i/o process,
it could corrupt the data" isn't really a good argument, because if
the process hangs and I have to punch the reset button anyway what's
the difference?

Ideas?
-Modulok-