Path: utzoo!attcan!uunet!know!cs.utexas.edu!uwm.edu!uwvax!titanic.cs.wisc.edu!tonyrich
From: tonyrich@titanic.cs.wisc.edu (Anthony Rich)
Newsgroups: comp.sys.mac.hardware
Subject: Re: REMOVABLES TRASHING HARD DISKS ???!!!
Message-ID: <11341@spool.cs.wisc.edu>
Date: 24 Sep 90 23:45:30 GMT
References: <9549.26f8a1f0@rsmas.miami.edu> <1990Sep21.140502.8273@ariel.unm.edu>
Sender: news@spool.cs.wisc.edu
Organization: U of Wisconsin CS Dept
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>> So, the obvious question is "Are removables (perhaps Syquest's in
>> particular) trashing hard drives for no reason?". 

My wife tells me "There's a reason for *everything*; it's just that you may
not *understand* the reason."  (...I don't know WHY she tells me that. ;^)

I think the "trashed hard drive" problem might be a general SCSI termination
problem.  Last spring I put together a Teac 150MB backup tape drive from a
raw drive and an enclosure/power supply.  I found out *immediately* that if
I turned off the Teac while the Mac II was still running, the hard drive
directory got trashed on the very next event (i.e., double-clicking a folder).

I posted a question about it on the net this summer, and people who know the
mysteries of SCSI termination told me that my Teac's termination power is
apparently drawn from the enclosure rather than the SCSI bus, so turning off
the enclosure's power brings down the whole SCSI chain.  Evidently that can
cause corruption of the (internal) hard disk directory, too.

Perhaps the reported problem with the Syquest removable is related.
Termination problems can be tricky.

My particular solution has been simply to shut down the Mac first, turn off
the Teac and unplug it, then restart the Mac.  It's inconvenient, but I can
live with it.

So the reported problem *may* be more generic; don't be too quick
to blame Syquest removables in particular.

  -- Tony

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