[1731] in linux-scsi channel archive
Re: Adaptec: all three buses used
daemon@ATHENA.MIT.EDU (Jeffrey Wiegley)
Sun Apr 20 19:36:01 1997
Date: Sun, 20 Apr 1997 16:31:09 -0700
From: Jeffrey Wiegley <wiegley@usc.edu>
To: Niels <niels@holding.pi.net>, linux-scsi@vger.rutgers.edu
Actually this is the incorrect way to do it. The bus isn't terminated
correctly and you could get errors with this.
The proper way to get external narrow devices while still having both
internal wide and noarrow devices is to simply run the internal narrow
cable out the back of the computer. That way everything is connected to
the internal connector.
I purchased a small expansion port cover that has a 50pin dense
connector on the outside and a 50pin narrow socket on the inside. you
simply plug the end of the internal cable into this and now you have a
socket on the outside identical to that presented by the card itself.
By terminating last device on the chain outside you now have the proper
termination. If you ever remove your external devices you can still
maintain proper termination by simply attaching a terminating resistor
pack to the outside connector in place of any devices. This all cost me
only around $30.00 for the terminator pack and the internal/external
connector.
That's my two cents. I could be wrong but this thread has come up before
and followed the advice from then and everything has worked 100% for me
and it all makes sense and seems to conform to what the manual(s) needed
for termination.
- Jeff
Niels wrote:
>
> Hi all,
>
> I vaguely recall a thread here, some time ago, about placing devices on
> all three buses of an Adaptec 2940(U)W.
>
> I just did it.
> External: Iomega ZIP Drive. (man, expensive cabling!).
> Not terminated.
> Internal Small: Iomega ZIP Drive (internal), and an IBM 2GB disk.
> Internal Wide: IBM 2.2GB.
>
> The catch seems to be to make the external ZIP Drive not terminate, and
> the others auto-terminating. I did a copy from the first ZIP to the
> second ZIP, and several find's on the other disks, no SCSI bus resets or
> any such nastiness in dmesg output. (the copying was slow, btw...)
>
> Niels
>
> -- --- -------------- ----------------------- -------------- --- --
> PIH XXTP SE ICTL, BTIHTKY. <niels@churchofbofh.org>
> Note: I do not speak for my employer - they have net.access too.
