Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!purdue!mentor.cc.purdue.edu!nova.cc.purdue.edu!gerrit
From: gerrit@nova.cc.purdue.edu (Gerrit)
Newsgroups: comp.sys.next
Subject: Re: fixing bad superblocks
Keywords: NeXT bad block optical disk
Message-ID: <1740@mentor.cc.purdue.edu>
Date: 14 Mar 89 04:02:22 GMT
References: <1208@blake.acs.washington.edu>
Sender: news@mentor.cc.purdue.edu
Reply-To: gerrit@nova.cc.purdue.edu (Gerrit)
Organization: Purdue University
Lines: 27

In article <1208@blake.acs.washington.edu> corey@blake.acs.washington.edu (Corey Satten) writes:
>Fixing trashed optical disk superblocks on NeXT 0.8.
>
>I have just fixed the 3rd (on campus) trashed superblock on a NeXT
>optical disk.  My current hypothesis is that shutting down via the
>power button instead of running /etc/halt is the cause.  Fortunately,

I remember a comment about this at the 3rd NeXT developer's camp.  When
they were going through "basic training" on the machine (booting, mounting,
shutting down, etc) they told people let the machine sit for 60 seconds at
some point near the end of a shutdown.  I believe it was either just before
powering off the machine or just after typing halt (I'm one of those who
never shuts down my workstation, so my memory of the timing is fuzzy).
Maybe someone else who was there will find this a refresher and fill in
the details I'm forgetting.

Anyway, the problem was that some quirk of Mach which prevents data from
getting actually flushed to disk until some long timeout (something less
than 60 seconds) had passed.  The moral:  warn people not to power off
their machine without a 60 second pause *somewhere* near the end.  Again, I
apologize for the lapse in memory, and I hope someone remembers what I'm
not.

Gerrit Huizenga,
Purdue University Computing Center
NeXT Workstation Coordinator
gerrit@mentor.cc.purdue.edu