Thanks to:
alan_at_nabeth.cxo.dec.com
"John J. Francini" <francini_at_progress.com>
"Heater, Gene" <Gene.Heater_at_echostar.com>
Rodrigo Poblete <rpoblete_at_gmd.com.pe>
I don't know exactly if it's a terminator, but there is a tiny breadboard
that could very be the terminator indicated in the responses. Thanks for
the info and confirmations!
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original question
=============================================================================
Greetings -
I'm helping another admin who has a 2100 and unfortunately no manuals. I
think I just need a quick confirmation/verification from someone:
It has a single SW shelf, extended from the removable-media-scsi-bus, and
only ONE controller instead of two. By process of elimation, it seems as
if the shelf ID's are as follows for dual controller config:
0 0 1 1 2 2 3 3
Where each controller has four drives (0-3) at it's disposal? So, for our
situation, a single controller config, does the shelf auto-assign ID's as:
0 (4) 1 (5) 2 6 3 (7)
Where the single controller treats the drives as 0-7 except interleaved?
Furthermore, in a single controller config, this implies that you can only
use 5 drives total (since 4,5,7 are reserved)?
=============================================================================
response
=============================================================================
The shelf in the 2100 and the controller connected to it
are independent. That shelf could be used with a bare
SCSI adapter or a backplane array controller. The shelf
doesn't know the difference.
My (limited) experience with the shelf shipped in the 2100
systems is that is split into two independent SCSI busses.
This was an early (perhaps original) design feature of the
StorageWorks shelf. I believe that's why you see the ID
pattern that you do. The BA350 versions of the shelf have
a terminator and jumper that can be swapped to have a single
bus. I don't know if the shelf used in the 2100 has a
similar jumper, or it was always intended to be used as
two busses. I've never seen documentation for the shelf.
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response
=============================================================================
On _some_ StorageWorks shelves there's a jumper on the back (kinda like a
SCSI terminator), which, if moved from one spot to the other, will make the
bus in the shelf a single one, running from 0 to 7 from one end to the
other. The jumper is on the back of the SW shelf, so you may have to
remove the shelf from the 2100 to check it out.
And it does imply that you can only put 5 drives in there, otherwise they
will conflict with the CD-ROM, built-in tape drive (if fitted), and SCSI
controller.
Alternatively, you could leave the SW shelf as is and pick up a compatible
single-ended SCSI card, like the KZPDA-AA, and be able to use all the
slots. They shouldn't be terribly expensive.
Just a thought,
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response
=============================================================================
There are two ways that the SW shelf acan be configured depending on
the positioning of the terminators on the back of the shelf. The first
is 0 4 1 5 2 6 3 7 . The second is the 0 0 1 1 2 2 3 3.
I think that switching the terminators toggles the configurations but I
have never tried it myself.
=============================================================================
response
=============================================================================
The 2100
has an internal shelve whose IDs are assigned as follows:
from top to bottom
0 4 1 5 2 6 3 7
Id 7, the bottom, is hardware disabled.
The shelf can be partitioned in two via a terminator connector
that goes on the back of the shelf.
By default it comes wired for a single partition
and the IDs are assigned as mentioned above
If you install the terminator connector, you will get two
separate partitions or buses for your shelf
and the assignments will go like this:
bus one 0 1 2 3
bus two 4 5 6
Phisically, the IDs are ALLWAYS interleaved as indicated in the beggining,
there's no way that you can modify this.
=============================================================================
thanks and cheers,
_____________________________________________________________________________
Ian Veach, Postmaster/Webmaster/Sysadmin, UCCSN System Computing Services
ivo_at_nevada.edu, VOICE: (775) 784.6486, FAX: (775) 784.1108
_____________________________________________________________________________
Received on Thu Jul 01 1999 - 20:45:55 NZST