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Conference ssag::ask_ssag

Title:	Ask the Storage Architecture Group
Notice:	Check out our web page at http://www-starch.shr.dec.com
Moderator:	SSAG::TERZAN

Created:	Wed Oct 15 1986
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	6756
Total number of notes:	25276

6421.0. "No 16 bit differential shelf module?" by EVMS::PIRULO::LEDERMAN (B. Z. Lederman) Mon Feb 24 1997 09:21

    I've looked for this in this and other notes conferences, but didn't
    see anything.
    
    I recently got a 16 bit BA356 shelf working with the KZPSA adaptor on
    an AlphaServer 2100.  I was a bit dismayed by the fact that I had to
    hook up an extra cable and a DWZZB box (with an extra power cord, and
    NO indicator light to tell me if the power was on) in order to do this.
    
    It seems an unneccessary complication to have to go through all of this
    to put a wide box on a wide adaptor.
    
    Isn't there a differential 16 bit I/O module, so I can just run one
    cable from the KZPSA (or equivalent) to the shelf and be 16 bit
    differential the whole way with no extra converter boxes and cables?
    
    And aren't most of our 16 bit boards (at the CPU end) differential? Why
    would the 16 bit I/O module be single ended anyway?

T.R	Title	User	Personal Name	Date	Lines
6421.1	You are correct	JULIET::SMITH_P		`Tue Feb 25 1997 08:08`	8
	In a perfect world you are correct and somewhere in the near future you will see this problem resolved. The shelves in question are multipurpose and are also used behind controllers, HSJ, HSD, HSZ and they are FNSE. The real fix is one module that can support FWD. Go talk to Storage staff to explain futures and you will see the light. Paul
6421.2		SUBSYS::BROWN	SCSI and DSSI advice given cheerfully	`Wed Feb 26 1997 08:52`	2
	Have you considered the DWZZB-VW, which occupies one slot in a BA356 box, instead of the tabletop model DWZZB-AA ?
6421.3	Tried it, didn't work.	EVMS::PIRULO::LEDERMAN	B. Z. Lederman	`Wed Feb 26 1997 11:10`	11
	\| <<< Note 6421.2 by SUBSYS::BROWN "SCSI and DSSI advice given cheerfully" >>> \| \| Have you considered the DWZZB-VW, which occupies one slot in a BA356 box, We have one, but when we hook it in instead of the 16 bit shelf, we have problems if there are any wide drives in the box (like the system hangs). If in fact the DWZZB-VW is supposed to connect a wide differential cable from the CPU to wide drives in the BA356, then something is wrong somewhere.
6421.4	I smell a rat	SUBSYS::BROWN	SCSI and DSSI advice given cheerfully	`Wed Feb 26 1997 13:47`	7
	I couldn't agree with you more! The system should not be hanging. If the table-top DWZZB works, and the DWZZB-VW doesn't, then you have a defective DWZZB-VW. Please borrow another one and try again. Also, check whether the system hangs when all the drives are wide, or only when you use a mix of wide and narrow. Some of the older narrow drives don't play nicely on a wide bus.
6421.5		EVMS::PIRULO::LEDERMAN	B. Z. Lederman	`Thu Feb 27 1997 05:11`	1
	The hang occurs with all wide drives in the box.
6421.6		SUBSYS::NEUMYER	Here's your sign	`Thu Feb 27 1997 12:46`	5
	There is a new series of personality modules that will operate up to ULTRA SCSI coming, both differential and single ended. ed