Subject: Re: SCSI network
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Bill Studenmund <>
List: tech-kern
Date: 10/01/1999 11:37:52
On Fri, 1 Oct 1999, der Mouse wrote:

> I'm contemplating using SCSI interfaces as a networking medium.  Does
> anyone have any thoughts on where I should look for (a) convincing a
> machine that it should speak on other than ID 7 or (b) convincing a
> machine to respond as if it were a drive, ie, to respond to another
> device on the bus attempting to contact it?  If necessary I'm prepared
> to make the link asymmetric, with one of the hosts distinctly in
> control of what happens, though I'd prefer to avoid that.

As others have mentioned, teaching the controller to not be ID 7 shouldn't
be too hard. But teaching it to be a target is harder. :-)

One other note, from one of the AIX lists I was on way back when. AIX had
the two-hosts-on-a-bus trick for quite a while. The recomended practice
(at least on the list) was to make one host use ID 6, and the other ID 5.
That way you didn't have anything at ID 7. Why? Because all of the POST
(PowerOn SelfTest) code would set the SCSI controller up to be ID 7. Thus
if you wanted one a 7 and one at 6, the one at 6 would actually be at 7
while booting. With the normal operating #'s not at 7, things were fine as
long as you didn't boot both machines at once.

Take care,