[rescue] External SCSI on SGI Challenge L

Sheldon T. Hall shel at cmhcsys.com
Sat Dec 20 18:08:26 CST 2003

Growls the Bear ...
> On Nov 26, 2003, at 12:36 PM, Sheldon T. Hall wrote:
> > My "new" Challenge L has a connector for an external SCSI chain, but a
> > quick look inside the machine discloses that the cable to the external
> > connector is not connected to anything.
> >
> > A more lengthy look inside the machine fails to find anyplace to
> > connect the thing.
> The connector is wired as standard-issue (I mean, "not connected to
> anything" is the way it shipped from SGI). It is present in case one
> wishes to repurpose one of the two "internal" SCSI busses as an
> external one.
> There are two SCSI busses built-in to the IO4, which uses "personality
> modules" to configure their behavior as either single-ended or
> differential. There is a jumper on the single-ended personality module,
> which needs to be installed to configure it for "external" operation.
> This jumper is not present on the differential personality module.
> The idea was, if you needed an external bus, you simply pulled one or
> the other of the cables running to the internal drive bays, and cabled
> the bulkhead connector in its place.

Ah.  OK.  Clever.

Is there also a way to make all the internal bays run off one of the
controllers on the IO4?

Next question ... if I get another IO4, what do I have to do to make it
appear as controllers 2 and 3, so I can use two IO4s in the same Challenge?


PS: You owe me e-mail about the shelf, sleds, and whatnot, non?

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