[SunRescue] scsi cable order

[James Lockwood]

On Thu, 15 Feb 2001, jeff borisch wrote:

> 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. 

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

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.

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. 

5MB/s narrow SCSI is amazingly forgiving by SE standards.  If something is
making a drive not work it has to be seriously broken.

> 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.

-James