Summary: Trouble adding SCSI disk

From: James J Dempsey (
Date: Sun Mar 03 1991 - 17:00:08 CST

Last week I described a problem whereby I couldn't add a Wren V to a
3/60 that already had a Sun shoebox and two Pinnacle Micro
magneto-optical drives. Whenever the Pinnacle drives were in the SCSI
chain, the Wren wasn't visible.

Virtually everyone who responded suggested that this was a SCSI
termination problem. They said that the Pinnacle drives were probably
internally terminated.

At first I was convinced that this wasn't the case because:

   1. The two Pinnacle drives had been working for 2 years in the
        middle of a SCSI chain.
   2. Each of the Pinnacle drives came with an external terminator.
   3. The Pinnacle documentation never mentioned internal terminators,
        but explicitly said to use the external terminators if the drive
        was at the end of the chain.

However, after calling Pinnacle it turned out that both of the drives
had been shipped with internal terminators. It had just been a
coincidence that the configuration had worked for two years. I
removed the internal terminators and then everything worked fine.

Thanks to those who responded:

Daniel Strick <>
Jim Guyton <>
Wolfgang Wetz <>
Kevin Sheehan {Consulting Poster Child} <sundev!fletch!>
Rick Niziak <ontologic!gremlin!>
George Ross <>
Jeff Byers System Admin <accutec!>

                --Jim Dempsey--

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