NFS hangs the system on failures because it is a shoddy implementation, not because it happens to be implemented in kernel space. I think the old CVS quote by

NFS hangs the system on failures because it is a shoddy implementation, not because it happens to be implemented in kernel space. I think the old CVS quote by Tom Lord applies here: CVS has some strengths. It's a very stable piece of code, largely because nobody wants to work on it anymore.