HELP

[Doug Ledford]

Richard Couture wrote:
> 
> Thank you all for your many observations, explanations, and
> suggestions, both on the list and privately.
> After reading them all I decided on the following course of action:
> 
> I removed the drive from it's external case and installed it
> internally.  This eliminated the expensive, high quality cable that
> was used to connect it to the SCSI external connector as well as the
> active terminator, and of course the power supply.
> Since this was the only thing on the external chain, I terminated the
> card.
> 
> Thus far the backup seems to work without a hitch.  I am sorry that
> the solution changed so many variables as to make it impossible to
> determine precisely which was the culprit, but it all works now and I
> am very happy.
> 
> The drive still negotiates at 6.67 MBps.

Hmmm...so moving the drive to internal improved reliability and operation. 
Well, that would normally mean a termination problem when the drive was
external.  However, you noted that you had termination disabled on the card
and an active terminator plugged in after the tape drive.  I think there is
one other thing that could have been wrong.  When you disable termination on
the card, it also disables the power to SCSI pin 26 on the card as well
(Term Power).  If other devices on the bus don't make up for this missing
term power source, then there could be a problem.  You need at least one,
and on longer busses possibly two, sources of term power.  Without any term
power that external active terminator wouldn't have worked.  But, if you
only had one source of term power, such as the internal hard drive all the
way at the other end of the cable, then the quality of that power to the
external active terminator could have been marginal.  It very well may be
the case that if you had another source of term power on the bus closer to
that active terminator that things might have started working OK.  Just a
thought :)

-- 

 Doug Ledford  <dledford at dialnet.net>
  Opinions expressed are my own, but
     they should be everybody's.

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