[rescue] External SCSI on SGI Challenge L

r.stricklin bear at typewritten.org
Sat Dec 20 18:08:25 CST 2003

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.


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