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Path: utzoo!linus!decvax!ima!inmet!faust!brianu
From: brianu@faust.UUCP
Newsgroups: net.rumor
Subject: Re: Orphaned Response
Message-ID: <14500002@faust>
Date: Wed, 26-Feb-86 16:11:00 EST
Article-I.D.: faust.14500002
Posted: Wed Feb 26 16:11:00 1986
Date-Received: Mon, 31-Mar-86 04:01:37 EST
References: <1036@burl.UUCP>
Lines: 29
Nf-ID: #R:burl.UUCP:1036:faust:14500002:000:1650
Nf-From: faust.UUCP!brianu    Feb 26 16:11:00 1986


Cray XMP computers have a thing called "The Peripheral Expander Chasis".
It is used to store the object image of the Operating System.
Anyway, the old version of this chasis included an 80-megabyte disk
drive that had the "feature" of sometimes being able to recover from
a head crash.  What this means is that a single head crash will kill
your disk, but the heads may be o.k. (or not).  Subsequent reads and
writes will either work o.k. or get i/o errors which may damgage
damage new areas of the disk pack.  In any case, there is no
indication that the problem was a head crash.
  Originally, the Cray was booted from the tape drive, but a new
version of the O.S. gave us the ability to boot from the disk (much
faster). So, for safety's sake we made backups on all our packs and
onto tapes.  What we didn't know was that we had had a head crash
when making the first backup to disk.  We booted o.k. for a while
(reads were o.k.) but when we changed a file on the disk, it
suddenly stopped working.  We tried the backups, but they all failed;
each in a different way, and so did the tapes (made from bad disks
remember). We thought we had a problem in the cables or something.
====================================================================
Gen: And do you mean to say that you would deliberately rob me of
  these the sole remaining props of my old age, and leave me to go
  through the remainder of life unfriended, unprotected, and alone?
Pirate: Well, yes; that's the idea.

Brian Utterback     Intermetrics Inc.
733 Concord Ave. Cambridge MA. 02138. (617) 661-1840
UUCP: {cca!ima,ihnp4}!inmet!faust!brianu
Life: UCLA!PCS!Telos!Cray!I**2