> kill -9 doesnot work Lots of things can get processes into an unkillable state. The most common one is if the process is in the middle of core dumping - linux won't let you kill it till it has finished writing the core file (which might take decades if it happens to be writing the core file over a slow network link). If the process is being debugged it can also get into a state where it won't go away with a kill -9, though usually a kill -CONT will get it running enough to notice the kill -9. Then there are just plain old bugs, like the process being in a system call with some mutex locked forever.
