The Jargon File (version 4.4.7, 29 Dec 2003):

Nightmare File System
 n.

    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.


The Free On-line Dictionary of Computing (30 December 2018):

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]