Re: old 68pin cables for 'new' U320 cards and HDDs ? ok ?

"Folkert Rienstra" <see_reply-to@xxxxxxxx> wrote:

>"Bruce Morgen" <editor@xxxxxxxx> wrote in message news:8m1tt19jbt0btd03neia5t73mblek1l5da@xxxxxxx
>> "ygs" <ys@xxxxxxxxxxxxxxx> wrote:
>>
>> > Hello,
>> >
>> > I have a couple of old 68pin scsi cables used now with UltraSCSI wide
>> > card and old scsi 7.5K RPM drives.
>> >
>> > Does anybody know is it possible to use these cables with new U320
>> > cards with 68pin interfaces ?
>> >
>
>> A very bad idea.
>
>Nonsense.
>
>> First of all, the new LVD-capable drives don't have built-in termination
>> and the end connector generally isn't close enough to it closest neighbor
>> for a proper terminator to work correctly
>
>So in your words the old cables never even existed because
>they couldn't work. Sounds like a big dilemma.
>
The old cables worked fine
for non-LVD signalling and
still do, but the guy is
equiring about using one
with a U320 drive.

>> -- iirc, an LVD-capable cable has its conductors arranged in twisted
>> pairs for improved noise immunity
>
>> and has the last two connectors very close together to enable effective termination.
>
>What a load of bollocks.
>Nowhere does it say that you always have to use the last connector.
>A terminator terminates the cable, not the last device.
>The (fixed) terminator sits close to the last device so they can count as one
>device. Else it would have to sit at normal device spacing and they count as 2.
>There is nothing wrong with a cable that has evenly spaced connectors
>with a detachable terminator connected at the end connector.

So a terminator "can count
as a device?" Interesting
-- how would one set the
SCSI ID of a terminator
"device?"
>
>Obviously you have no idea what termination is.
>
I know that in over twenty
years of using SCSI devices
I've never seen a terminator
with a SCSI "device" ID or
connected anywhere other at
an end of the physical SCSI
chain -- have you, are you
blowing technoid smoke of no
practical value?
>>
>> Bottom line imo: get a cable intended for modern LVD signalling --
>
>> the old stuff just won't cut it,
>
>It may work fine short stretches

That was my point, Folkert
-- it "may" or it "may"
not, iow it can't be relied
upon to "work fine!"
>
>> at least not reliably.
>
>Actually, Ultra320 has extras just to ensure that.
>It may not run at highest possible speed, but will run reliably.
>
OK, you've stretched the idea
of reliability to include
running at half the bus speed
a U320 device is capable of
(or less!) -- congratulations,
I guess.....



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