[SunRescue] scsi cable order

jcarver rescue at sunhelp.org
Thu Feb 15 13:33:14 CST 2001


Good point Jeff. I usually have best results using the longest cable
as first one off the CPU. I also see I left out an important adverb on
the line about internal termination(should be "have an internal device
NOT terminated. = p.

As to the IPX , techically it's on a stub off the bus. Drives are not term.
from the factory. I've gotten away with no term. on the output of Sun 4c's,
that is with no external devices attached. Of course we are are only dealing
with 5mb Scsi. If I attach a CDROM or other device. then I terminate.

                                                        jim

                                                        jim

jeff borisch wrote:

> Good advice about termination.
>
> Sometimes it is worth it to check if an external box is terminated
> internally with a jumper on the drive's circuit board, an internal
> terminator or a termination switch somewhere on the case. I've seen that be
> a problem.
>
> Put that device at the end obviously, or remove the jumper or other source
> of termination and just use an external terminator on the plug on the case.
>
> Also, the magical nature of scsi can make things "just not work" as well as
> "just work". The order of cables and devices /can/ make the difference. Seen
> it myself, mmmmmm.
>
> Unfortunately with three external boxes and three cables to work with you
> have 36 possible configurations. The good news is most of them will probably
> work.
>
> jcarver wrote:
>
> > The order of the boxes isn't important. Make sure that the
> > address number in the window on the back of the external
> > device has not changed, i.e. CD is still @ 6, etc. and make sure
> > that the terminator is installed on the last box in the chain. I am
> > assuming that these are all Sun boxes that have an internal device
> > terminated.
> >
>
> I can't remember if the IPX needs the internal drive terminated or not. From
> what I understand the ss2's drives are on the bus with 'stubs' and don't
> need to be terminated.
>
> --
>
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