[SunRescue] scsi cable order

jeff borisch rescue at sunhelp.org
Thu Feb 15 17:52:45 CST 2001


James Lockwood wrote:

> SCSI is not magic, it follows well understood rules of transmission line
> physics.

Shhhh! you'll anger the gods.
(-:
Actually, I wish I understood those physics better...

> If changing the order of your cables affects your setup (and you aren't
> doing something dumb like leaving a wide SCSI device with the high bits
> floating) then something is wrong with either your termination, cables, or
> devices.  Usually in that order.

That is good advice, I try to keep all devices on their most appropriate
interface. No wide to narrow adapters and all that.

> A number of SCSI cables produced _new_ do not meet spec.  Moving a bad one
> to a different section of the chain may reduce incident reflections enough
> to let it work, but the real solution is to cut it in half (so nobody else
> gets stuck with trying to make it work for hours) and get a new one.

(-: I've nearly cut apart some cables here at work, but they aren't mine. I
do put a loop of tape around them marked SUSPECT. Tell people not to use
them unless you are in a temporary jam.

>> 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.

> The IPX is the same way.

Thanks!


--jeff




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