[Tfug] SCSI disks

[Bexley Hall]

--- John Karns <johnkarns at gmail.com> wrote:

> On 8/20/07, Bexley Hall <bexley401 at yahoo.com> wrote:
> >
> > --- John Karns <johnkarns at gmail.com> wrote:
> >
> > > On 8/16/07, Bexley Hall <bexley401 at yahoo.com>
> wrote:
> > > > However, the LX uses "50 pin (SE) SCSI".  I've
> > > > never seen a 50 pin drive larger than 4G (but
> > > > I suspect they exist -- or existED!).  In any
> > > > case, I don't *have* such a device.
> > > >
> > > > *But*, I can probably find a *wide* SCSI drive
> > > > (non-SCA) of a larger size.
> > >
> > > > But, is this as "simple" as getting a cable
> > > > with a 50 pin berg connector on one end and
> > > > a 68 pin wide scsi connector on the other?
> > >
> > > Yes, I've done exactly that, connecting a 68-pin
> > > wide drive to an
> > > Adaptec 50-pin 1460 slim SCSI pcmcia card to
> read /
> > > write the drive.
> >
> > Ah, OK.  But, how did you handle the termination
> > on the drive end of the cable?
> 
> In the case I mentioned with the 50-pin pcmcia card
> connected to a 68-pin hd, I probably had the hd
> jumper set for termination on the drive.

Yes, *if* the drive has internal terminators (many
do not)

> In any event, it was just a temporary connection,
> so I didn't consider it critical to have proper
> termination.  Of course it's always a good idea 
> to verify the data after copying.

Understood.  In my case, the drive will be in a
box runnign 24/7 (though the old SPARCS have
dreadfully slow SCSI busses *and* its a short
run from "host" to "target")

> > I have lots of IDC (e.g., Berg-style) connectors.
> > But, *my* problem is the cables that I have are
> >
> > 68W --------------- 50SE ----- terminator
> >
> > I.e., they are expecting the "host" to be located
> > at the 68 pin end (with its on-board termination)
> > then, the narrow, SE drive on the 50 pin
> connector.
> > Finally, the terminator dangling off the end to
> > terminate the *drive* end of the cable.
> >
> > I would cut off the terminator in my application
> > since that would be the "host" end of the cable
> > (and the host is already terminated).  *But*,
> > there is no way to "extend" the 68 pin end to tack
> > a terminator on there for the *drive* end of the
> > cable!  So, I would have to count on the drive
> > having termiation onboard, etc.  (I haven't looked
> > into this, yet)
> 
> Since you said that the Sparc uses 50-pin SCSI, I
> assumed that:
> 
> 1) the controller was 50-pin
> 2) the cable was also 50-pin
> 3) the drive was non-SCA

The existing cable was 50 pin.  I.e. Narrow SE to
Narrow SE.  However, I want to mate the Narrow SE
controller to a *wide* SE/LVD (the LVD isn't an
issue since you can strap most SE/LVD drives to
be SE).  To that end, I stumbled across a cable
in my junque box that had the above illustrated
configuration.  *With* the problem of no excess 
cable on the 68W end (for a terminator) :<

> I'm not sure I'm clear about what you stated about
> the termination is
> on your setup.  AFAIK, there should be termination
> on both ends of the
> cable (SCSI host and hd end, as last device
> connected).

Yes.  The processor ("motherboard") has termination
on board.  Typically, a SE drive has provisions for
terminating RPAKs (i.e. 10-pin 220/330 networks)
so the termination on *that* end is handled by
installing a couple of RPAKs.

However, using a wide SCSI drive (68 pin, not 80 pin
SCA) doesn't usually give you that option  :<

> For clarity, I'll add that neither end should have
> multiple
> termination - e.g., if the drive is jumpered for
> termination, there
> should be no other termination device at that end of
> the cable.

Correct.
 
> In short, if you have a 50-pin, terminated
> controller with a 50-pin
> cable attached, and want to attach a 68-pin hd, all
> you should need to
> do is connect it with an adaptor and set the jumper
> on the drive for
> termination.  If the hd has no such jumper, then
> attaching a 50-pin
> terminator to the end of the cable should do the
> trick.

But the "end" of the cable that it needs to be
attached to is a 68 pin wide connector (i.e. there
is no "extra" cable to tack a spare connector onto,
etc. ).

<shrug>  Maybe I'll just *solder* some RPAKs onto a
drive and call it a "special"...


       
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