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Nightmare File System

   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.