One SCSI tape connected to 2 hosts?

From: Gary Hildebrand <ghldbrd_at_ccp.com>
Date: Sun Jun 16 18:56:40 2002

"Clint Wolff (VAX collector)" wrote:
>
> Hi Bob,
>
> I've tried to connect a tape drive between a Windows 95? machine
> and a FreeBSD machine with limited success. Windows issues a bus
> reset whenever it gets confused (translate a lot!) which will
> abort any transfer taking place from the MV3100. FreeBSD seemed
> to be better about not bothering with the bus except for reboots,
> but wasn't reliable WRT transfers.
>
> What you really need is a PC driver that accepts the fact it isn't
> the highest priority device, and leaves the bus reset line alone.
>
> Clint
>
> On Sun, 16 Jun 2002, 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.
> >
> > Doc
> >
> >

I've seen that done with SCSI HD's and Amigas, but the booting was
iffy. sometimes it worked, sometimes it would hang.

Too bad SCSI is underused; it is already overpriced. But what you can
(or could) do with it . . . .

Gary Hildebrand
St. Joseph, MO
Received on Sun Jun 16 2002 - 18:56:40 BST