Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!snorkelwacker!apple!amdahl!dgcad!gary
From: gary@dgcad.SV.DG.COM (Gary Bridgewater)
Newsgroups: comp.windows.x
Subject: Re: R4 Athena Widget question.
Message-ID: <1445@proa.SV.DG.COM>
Date: 7 Mar 90 08:52:24 GMT
References: <100920180@hpcvlx.cv.hp.com> <9003042232.AA01692@underprize.think.com>
Reply-To: gary@proa.SV.DG.COM ()
Organization: Data General SDD, Sunnyvale, CA
Lines: 50

In article <9003042232.AA01692@underprize.think.com> rlk@THINK.COM (Robert L. Krawitz) writes:
>
>   Date: 1 Mar 90 01:35:44 GMT
>   From: hp-pcd!hpcvlx!ben@hplabs.hp.com  (Benjamin Ellsworth)
>
>   Every UN*X system that I've used allows the programmer to create a
>   file, and then unlink it from the file system.  As long as it is not
>   closed, it exists known only by the program until it exits.  (The
>   Morris worm exploited this behavior.)  When the program calls exit(),
>   the system calls clean everything up very nicely.
>
>This doesn't work too well on NFS filesystems...

Whose? What rev? What fails?

Scenario:
	open local file
	remove file
	do stuff with file
	system crashed
	data is gone

Scenario:
	remote shell a program that opens a "local" file over "there"
	etc.

Scenario:
	open file on NFS mounted disk
	remove file
	do stuff with file
	server crashes
	server comes up
	continue doing stuff with file
	exit {data may hang around in funny named file - cron cleans up}

Scenario:
	open file on NFS mounted disk
	remove file
	do stuff with file
	"my" system crashes
	data is gone

The difference with the NFS mounted file is that it gets renamed to
a funny name instead of being instantly destroyed. It is gone in the
sense that if you or anyone reopens the same original name it will
not exist. How is this a problem? It is a bit of an inconvenience
but, to our site, very much worth it.
-- 
Gary Bridgewater, Data General Corporation, Sunnyvale California
gary@sv.dg.com or {amdahl,aeras,amdcad}!dgcad!gary
The impossible we understand right away - the obvious takes a little longer.