Nightmare File System

Pejorative hackerism for Sun's Network File System (NFS).

In any nontrivial network of Suns where there is a lot of NFS

cross-mounting, when one Sun goes down, the others often

freeze up. Some machine tries to access the down one, and

(getting no response) repeats indefinitely. This causes it to

appear dead to some messages (what is actually happening is

that it is locked up in what should have been a brief

excursion to a higher spl level). Then another machine

tries to reach either the down machine or the pseudo-down

machine, and itself becomes pseudo-down. The first machine to

discover the down one is now trying both to access the down

one and to respond to the pseudo-down one, so it is even

harder to reach. This situation snowballs very quickly, and

soon the entire network of machines is frozen - worst of

all, the user can't even abort the file access that started

the problem!

Many of NFS's problems are excused by partisans as being an

inevitable result of its statelessness, which is held to be

a great feature (critics, of course, call it a great

misfeature). ITS partisans are apt to cite this as proof

of Unix's alleged bogosity; ITS had a working NFS-like

shared file system with none of these problems in the early

1970s. See also broadcast storm.

[Jargon File]