One SCSI tape connected to 2 hosts?

From: Huw Davies <Huw.Davies_at_kerberos.davies.net.au>
Date: Fri Jun 21 09:12:11 2002

At 03:16 PM 16/06/2002 -0500, Doc wrote:
>On Sun, 16 Jun 2002, Bob Lafleur wrote:
>
> > I've noticed that my MV3100's SCSI host ID's are set to 6 - I thought
> > this odd, as host ID's are usually 7. Are all MV3100's set to 6, or is
> > mine unique? Anyway, I thought since my PC's host ID is 7, I could
> > connect my SCSI tape drive to both systems. So I ran a cable from one
> > connector on the back to my PC, and a cable from the other connector to
> > my MV3100. I figure it's a properly terminated chain, as each host
> > controller is terminated (I know the PC is, I assume the MV3100 is).
> >
> > It *seems* to work OK. But can anyone tell me for sure if this is
> > "legal"? I'm sure I'm looking for trouble if I try to use the same tape
> > drive from both systems at the same time, but as long as I don't do
> > that, is this an okay setup? It would sure beat changing cables every
> > time I want to move the tape drive from one system to the other.
>
>Bob,
> A few of the older SCSI "how-to" pages diagrammed just such a setup.
>I've never seen it done in real life, but it always looked like a
>reasonable idea to me, too.
> I just found out, talking to my boss, that both native Solaris and
>Veritas Volume manager support that type of configuration.
> It's also relevant that you can run IP-over-SCSI between hosts, and
>ISTR that the original Beowulf code provided just that for fast
>intra-cluster communication.

Of course Digital (and Compaq) supported systems with shared SCSI storage
under OpenVMS alpha - not surprisingly they were known as SCSI clusters.
You still needed ethernet for SCS traffic but it certainly worked.

Huw Davies | e-mail: Huw.Davies_at_kerberos.davies.net.au
                      | "If God had wanted soccer played in the
                      | air, the sky would be painted green"
Received on Fri Jun 21 2002 - 09:12:11 BST