Draft Minutes of SPI-2 Working Group - 3/10/97
Norm Harris x2230
nharris at eng.adaptec.com
Thu Mar 20 13:36:11 PST 1997
* From the SCSI Reflector (scsi at symbios.com), posted by:
* Norm Harris x2230 <nharris at eng.adaptec.com>
John Lohmeyer wrote:
> * From the SCSI Reflector (scsi at symbios.com), posted by:
> * John Lohmeyer <John.Lohmeyer at Symbios.com>
> I do not recall an agreement to limit the Apr 18th meeting to only Ultra3
> discussions. But I may have missed that discussion. The plenary meeting
> schedule slide that we voted on labeled the Apr 18th meeting as a SPI-2
> meeting with no specific limitations. I think an Ultra3 limitation would
> waste the availability of some valuable resources, particularly on such
> questions as how Figure 24 should be (or should not be) modified. I do not
> propose that we take a final action on the figure in April, just that we be
> allowed to review the figure with the experts that I expect to be present
> (and quite possibly not present in May).
> The point about the Adaptec data being essentially the same as the data we
> reviewed last year is made in agenda item 10. Does it really need to be
> repeated in agenda item 9?
> PS: I would agree that 'agreement' is a word that should be used sparingly
> regarding this topic. ;-)
> At 12:25 AM 3/20/97, Gene Milligan wrote:
> >>8. Proposed clarification to Fig. 24 [Ham]
> >>Bill Ham said that his data suggest that figure 24 should not be changed.
> >>Bill requested that this issue be dropped from the agenda. John Lohmeyer
> >>expressed concern that an inconsistency exists if the figure is not changed.
> >>John and Bill discussed changes that should and should not be made to the
> >>figure. The group agreed to review the figure again at the next meeting,
> >>after everybody has a chance to review the current proposed figure with
> > This should be clarified to refer to the May meeting, not the next meeting.
> >>9. Issues with LVD [Harris]
> >>Norm Harris began his presentation with a review of the development of LVD
> >>SCSI. The conclusion of Norm's presentation was that there are no
> >>demonstrable problems with LVD SCSI at 40 mega-transfers per second.
> >>the same signaling technology cannot be run at faster transfer speeds,
> say 80
> >>mega-transfers per second, without some changes to signaling technology,
> >>device count, or maximum cable length.
> > This omits the key observation of many of the attendees including myself
> >Bill Ham that this was a re-affirmation of the data reviewed and generally
> >agreed to last year.
> >>The group agreed to consider the proposals in more detail during a SPI-2
> >meeting scheduled for > April 18th in San Jose, CA.
> > I certainly do not think there was any such agreement. I know I
> >objected to the meeting addressing SPI-2 proposals. I don't think any votes
> >were taken and the minutes do not note any votes being taken. I recall that
> >there was agreement that the meeting would only address test results and
> >probably proposals for Ultra 3. Had there been a reversal of this
> agreement in
> >the plenary I would have objected.
> > Please note that item 15 of the minutes conforms my recollection.
> John Lohmeyer E-Mail: john.lohmeyer at symbios.com
> Symbios Logic Inc. Voice: 719-533-7560
> 4420 ArrowsWest Dr. Fax: 719-533-7036
> Colo Spgs, CO 80907-3444 SCSI BBS: 719-533-7950 300--28800 baud
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Wait just a minute gentlemen.
The data presented by Adaptec is NOT a repeat of what has been seen by
the committee. As I pointed out, this is the first multidrop Ultra 2
study. Secondly, our data deals specifically with a study of the effect
of asymmetry on system timing and signal integrity. I stand on my
statment that the group had seen no data on multidrop asymmetric
environments prior to our presentation. Perhaps early adopters of this
technology have seen such data and are convinced that Ultra 2 really
works. If there is such data availible elsewhere, then bring it!
We acknowledged in our presentation that our concern for the future
was based on data that Bill Ham has presented showing DC offset and
first pulse symmetry distortion. THESE ARE EFFECTS THAT ARE PRESENT
REGARDLESS OF DESIGN APPROACH. It is our belief based on our study so
far that the use of the asymmetric design approach dictated by the
current Ultra 2 standard interacts more adversely at higher frequency
than a traditional symmetric design. Whereas our studies show that Ultra
2 is viable, it will leave us with a design legacy which unnecessarily
complicates future generations.
Adaptec welcomes any and all discussion on Ultra 3. We also want to
excercise our right as long standing supporters of the SCSI standards
process to raise issues, and to respond in a responsible manner to those
questions that are posed. We intend to provide a response to those
questions against our findings so that all involved may
make their own judgements as to the merits of our proposal.
And by the way Gene, although I heard you mention your desire to have
Apil 18 be limited to Ultra 3, I recall no "agreement".
Norman H. Harris
Staff Advisory Engineer
Principal Member T10/T11
Mission Critical Subsystems Group
691 South Milpitas Blvd. MS-200
Milpitas, Ca. 95035
Ph. (408) 957-2230
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