Draft Minutes of SPI-3 Working Group

John Lohmeyer lohmeyer at ix.netcom.com
Tue May 12 13:33:43 PDT 1998

* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* John Lohmeyer <lohmeyer at ix.netcom.com>
A PDF version of these minutes is available at:


Accredited Standards Committee*
National Committee for Information Technology Standards (NCITS)

                                                   Doc. No.: T10/98-146r0
                                                       Date: May 12, 1998
                                                   Reply to: John Lohmeyer

To:      T10 Membership
From:    Ralph Weber / John Lohmeyer
Subject: SPI-3 Working Group Meeting -- May 4, 1998
         Colorado Springs, CO


1. Opening Remarks
2. Approval of Agenda
3. Attendance and Membership
4. SPI-3 Topics
4.1 Staged Contact Resistance (98-174) [Herrmann]
4.2 Load Compensation (97-281) [Novak]
4.3 Universal Backplane Annex (98-101) [Wallace]
4.4 Bias Reduction Proposal (98-156) [Bridgewater]
4.5 Dual Clocking Proposal (97-208) [Bastiani]
4.6 Test results on dual edge signals (98-113r0) [Bastiani]
4.7 Hot Swap Technical Issues (98-155r0) [Uber]
4.8 QAS review (97-199r8) [Moore/Lamers]
4.9 CRC on existing SCSI parallel protocol (98-144r1) [Penokie]
4.10 Terminator Power voltage level [Wallace]
4.11 Simplified Parallel SCSI CRC Proposal (98-150r0) [Gardner]
4.12 Proposal for Fast-80 (98-152r0, 98-153r0) [Milligan]
4.13 Analysis of Fast-80  (98-160r0, 98-161r0, 98-162r0) [Smith]
4.14 CRC Proposal (98-154r0) [Leshay]
4.15 Old Expander Proposal (98-157r0) [McGrath]
4.16 New Expander Proposal (98-158r0) [McGrath]
5. Meeting Schedule
6. Adjournment

Results of Meeting

1.   Opening Remarks

John Lohmeyer, the T10 Chair, called the meeting to order at 9:05 a.m., Monday
May 4, 1998.  He thanked Symbios for allowing him to host the meeting.

As is customary, the people attending introduced themselves and a copy of the
attendance list was circulated.  John noted that standards cannot contain
known patented material unless the patent holder agrees to comply with the
ANSI patent policy.

2.   Approval of Agenda

The draft agenda was approved with the following additions and changes:

4.7 Hot Swap Technical Issues (98-155r0) [Uber]
4.11 Simplified Parallel SCSI CRC Proposal (98-150r0) [Gardner]
4.12 Proposal for Fast-80 (98-152r0, 98-153r0) [Milligan]
4.14 CRC Proposal (98-154r0) [Leshay]
4.15 Old Expander Proposal (98-157r0) [McGrath]
4.16 New Expander Proposal (98-158r0) [McGrath]

The following agenda items were added during the course of the meeting:

4.13 Analysis of Fast-80  (98-160r0, 98-161r0, 98-162r0) [Smith]

3.   Attendance and Membership

Attendance at working group meetings does not count toward minimum attendance
requirements for T10 membership.  Working group meetings are open to any
person or organization directly and materially affected by T10's scope of
work.  The following people attended the meeting:

         Name          S        Organization         Electronic Mail Address
---------------------- -- ------------------------- -------------------------
Mr. Lawrence J. Lamers P  Adaptec, Inc.             ljlamers at ix.netcom.com
Mr. Vincent Bastiani   A# Adaptec, Inc.             bastiani at corp.adaptec.com
Mr. Wally Bridgewater  A# Adaptec, Inc.             wally at eng.adaptec.com
Mr. Mark Delsman       A# Adaptec, Inc.             mdelsman at corp.adaptec.com
Mr. Steven P. Ego      O  Aeronics Inc.
Mr. Jeffrey Crockett   V  Aeronics Inc.             jeffreycrockett at worldnet.
Mr. Scott Lindstrom    O  AMP, Inc.                 slindstr at amp.com
Mr. Ron Roberts        A  Apple Computer            rkroberts at aol.com
Mr. Robert C. Elliott  P  Compaq Computer Corp.     Robert.Elliott at compaq.com
Mr. Bill Galloway      A  Compaq Computer Corp.     Bill.Galloway at compaq.com
Mr. Charles Tashbook   P  Dallas Semiconductor      charles.tashbook at dalsemi.
Mr. Greg McSorley      P  Data General / Clariion   greg_mcsorley at dg.com
Dr. William Ham        A# Digital Equipment Corp.   bill.ham at digital.com
Mr. Don Vohar          A  Fujitsu (FCPA)            dvohar at fcpa.fujitsu.com
Mr. George Penokie     P  IBM Corp.                 gop at us.ibm.com

Mr. Dan Colegrove      A# IBM Corp.                 colegrov at us.ibm.com
Mr. Dean Wallace       P  Linfinity Micro           75671.3443 at compuserve.com
Mr. Chuck Grant        A  Madison Cable Corp.       charles_grant at madisonusa.
Mr. Pete McLean        P  Maxtor Corp.              pete_mclean at maxtor.com
Mr. Jay Neer           A  Molex Inc.                jneer at molex.com
Mr. Chris Millsaps     V  Mylex Corp.               chrism at mylex.com
Mr. Edward A. Gardner  P  Ophidian Designs          eag at ophidian.com
Mr. Skip Jones         P  QLogic Corp.              sk_jones at qlc.com
Mr. Ting Li Chan       A  QLogic Corp.              t_chan at qlc.com
Mr. Chuck Micalizzi    V  QLogic Corp.              c_micalizzi at qlc.com
Mr. James McGrath      A# Quantum Corp.             JMCGRATH at QNTM.COM
Mr. Bruce Leshay       V  Quantum Corp.             bleshay at tdh.qntm.com
Mr. Richard Uber       V  Quantum Corp.             duber at tdh.qntm.com
Mr. Gene Milligan      P  Seagate Technology        Gene_Milligan at notes.
Mr. Gerald Houlder     A  Seagate Technology        Gerry_Houlder at notes.
Mr. Daniel (Dan) F.    O  Seagate Technology        daniel_f_smith at notes.
Smith                                               seagate.com
Mr. Mayank R. Patel    V  Seagate Technology        Masiewicz at notes.seagate.
Mr. Dave Guss          P  Silicon Systems, Inc.     dave.guss at tus.ssi1.com
Mr. Robert N. Snively  P  Sun Microsystems          bob.snively at sun.com
                          Computer Co
Mr. John Lohmeyer      P  Symbios, Inc.             lohmeyer at ix.netcom.com
Mr. Ralph O. Weber     A  Symbios, Inc.             roweber at acm.org
Mr. Graeme Weston-     A# Symbios, Inc.             gwl at symbios.com
Mr. Kevin Bruno        V  Symbios, Inc.             kevin.bruno at symbios.com
Mr. Frank Gasparik     V  Symbios, Inc.             frank.gasparik at symbios.
Mr. Tracy Spitler      V  Symbios, Inc.             tracy.spitler at symbios.com
Ms. Joy Godbee         V  Symbios, Inc.             joy.godbee at symbios.com
Ms. Kathleen Perkins   V  Symbios, Inc.             kathleen.perkins at symbios.
Mr. Bill Schmitz       V  Symbios, Inc.             bill.schmitz at symbios.com
Mr. David Steele       V  Symbios, Inc.             david.steele at symbios.com
Mr. Pete Tobias        A# Tandem, a Compaq Company  tobias_pete at tandem.com
Mr. Paul D. Aloisi     P  Unitrode Corporation      aloisi at unitrode.com
Mr. Jeffrey L.         P  Western Digital           Jeffrey.L.Williams at wdc.
Williams                  Corporation               com

47 People Present

Status Key:  P    -  Principal
             A,A# -  Alternate
             O    -  Observer
             L    -  Liaison
             V    -  Visitor_

4.   SPI-3 Topics

4.1  Staged Contact Resistance (98-174) [Herrmann]

In the absence of Hank Herrmann, discussion of this topic was deferred to the
July meeting.

4.2  Load Compensation (97-281) [Novak]

Vit Novak was not available to discuss this topic.  Questions were raised
about whether additional discussion was necessary on this topic.  A review of
the last meeting minutes indicated that a discussion of where to put the
information in SPI-3 should be discussed. Conversely, it was noted that Vit
expressed a belief that his presentations were only informational.  The group
took no action on locating the information found in Vit's presentations in any
committee draft document(s).

4.3  Universal Backplane Annex (98-101) [Wallace]

Dean Wallace expressed concerns about the size of the universal backplane
annex, 12 pages.  George Penokie, Jim McGrath and several others reassured
Dean that 12 pages is not too big.  Dean repeated his concerns about the size

and asked that discussion be postponed to the next meeting so that he might
have a chance to distill the current material.  George asked that Dean not
distill useful information out of the annex.

4.4  Bias Reduction Proposal (98-156) [Bridgewater]

Wally Bridgewater presented a discussion of how the bias might be moved from
the terminator to the transmitter and receiver, considering the timing issues
involved.  He also described the value of removing the bias during high-speed
data transfer phases.

Wally also proposed scheduled reductions in driver strengths, or cutbacks, to
address ISI (InterSymbol Interference) problems.  The group discussed the
"cutback" proposal with attention to how much cutback should occur in any step
and how many symbol repetitions before a cutback step would occur.

4.5  Dual Clocking Proposal (97-208) [Bastiani]

Vince Bastiani requested that this item be deferred to the next meeting.

4.6  Test results on dual edge signals (98-113r0) [Bastiani]

Vince Bastiani requested that this item be deferred to the next meeting.

4.7  Hot Swap Technical Issues (98-155r0) [Uber]

Dick Uber presented a discussion of the sequences for pin mating during hot
plugging and then showed traces from a sampling oscilloscope.  Dick summarized
his presentation as follows:

o    Hot insertion events DO NOT cause problems during bus free times.
o    Hot insertion events DO NOT cause reversals of bus polarity during data
o    Glitches that are superimposed on either asserting or negating
     transitions have the potential to shift the transition in time. This 
		 would cut into the setup and hold time margins.
o    Because of the huge time delay between the mating of the contacts for a
     differential signal pair, the bus may have to operate for an extended 
		 time with a load half connected. The imbalance causes a signal 
		 distortion, which can affect setup and hold time margins.
o    No problems with Hot Swap Case 4 were found during this testing. However,
     please note that the drives used for this testing measured well under 
		 the allowed 20pF capacitance limit.

Dick provided the following conclusions:

o    Case-4 Hot Swap has been demonstrated to work satisfactorily.
o    Testing has not been exhaustive, and has been limited to one backplane
     construction and one vendor's disk drives.

Dan Smith noted that Seagate has observed similar results in their testing.

The SPI-2 description of case 4 hot-plugging was reviewed.  Gene Milligan
closed the discussion by noting that it is hard to say you will not get errors
and difficult to say you will never get undetectable errors.  Gene concluded
that everything points to the importance of adding CRC when the transfer rates
are increased.

4.8  QAS review (97-199r8) [Moore/Lamers]

Larry Lamers presented the latest revision of the QAS proposal (97-199r8).
Questions were raised regarding statements in section 3.4 (Mixed Bus Blocking
Relief).  George Penokie agreed to review section 3.4 carefully and provide
comments to Larry.

The need for showing QAS capability in the Inquiry data surfaced, and Larry
reminded the group that a proposal on that topic has been waiting for
resolution of the 97-199 issues and will be brought to the next meeting.
Based on other discussion issues concerning section 3.4, Larry agreed to
propose adding a bit to the control mode page to control the fairness
algorithm as part of the Inquiry data (SPC-2) proposal.

Bruce Leshay repeated his concerns about snooping the bus for a 55h as a
message byte value.  Several cases were discussed and none produced the
problems that Bruce could show to be fatal.

Larry presented a timing comparison showing some QAS features (98-159).  The
group asked that the presentation be enhanced to compare QAS and non-QAS
timings.  Larry agreed to revise the charts for the July meeting.

4.9  CRC on existing SCSI parallel protocol (98-144r1) [Penokie]

George Penokie provided a quick overview of his CRC proposal.  One issue

raised concerned the potential requirement that the initiator crack the data
returned for commands such as Inquiry that may return less data than
requested.  George requested that rather than dealing with the outstanding
problems of his proposal, he would rather hear the other CRC proposals (see
items 4.11 and 4.14).  After all three proposals are heard, the group can
begin resolving issues.

4.10 Terminator Power voltage level [Wallace]

Dean Wallace asked that this item be removed from future agenda.

4.11 Simplified Parallel SCSI CRC Proposal (98-150r0) [Gardner]

Ed Gardner presented a proposal using a specifically encoded new bus phase, a
CRC phase (actually specific instances of the Data Out and Data In bus
phases).  Ed noted that the weakness of the proposal is the extra time
required turn the bus around from input to output or vice versa.  The CRC
discussion continued with Bruce Leshay's presentation (see item 4.14).

4.12 Proposal for Fast-80 (98-152r0, 98-153r0) [Milligan]

Gene Milligan presented 98-152r0, an overview of a Fast-80 proposal (called
Fast 80ish in the presentation), and distributed a proposal (98-153r0)
containing specific changes and additions to SPI-3 to support double-clocking
Fast-80.  Questions were raised about the relative values of the proposed
Transmit Hold Time and Transmit Assertion Period.  It was agreed that the two
8 ns numbers in the proposed Table 1 should be 10.55 ns.

Noting that time would be required to read the specific changes proposal, the
group requested two special ad hoc meetings to discuss Fast-80 issues.  The
agreement on ad hoc meetings is reflected in item 5.

4.13 Analysis of Fast-80  (98-160r0, 98-161r0, 98-162r0) [Smith]

Dan Smith presented three sets of test data supporting the proposed Fast-80
timings (98-160r0, 98-161r0 and 98-162r0).  Dan noted that his measurements
differed from those shown earlier by Wally Bridgewater.  The test methodology
was reviewed and Dan received some suggestions for improved future tests.

4.14 CRC Proposal (98-154r0) [Leshay]

Bruce presented a proposal that the Parity signal be reused as a CRC_Valid
signal for transfers where double-edge clocking is used.  He described the
reasoning that concluded with the proposal to reuse the Parity signal.
Concerns were raised about the use of the Parity (CRC_Valid) signal during
Data Out phase, as that use would require the signal to be driven in the
opposite direction from the data.

At the conclusion of all the CRC proposal presentations, George suggested that
his proposal (98-144r1) be set aside.  Questions were raised about possible
patents on the Bruce Leshay and Ed Gardner proposals.  Ed say that he would
not be applying for a patent and the Quantum representatives said that any
patents covering the 98-154 proposal would be licensed at no cost.

The group reduced the description of the choices to a choice between a high
performance CRC implementation that breaks existing bus expanders and lower
performance CRC implementation that does not break existing bus expanders.
With that realization, the group moved to discussion of the new expander
proposal (98-158r0, see 4.16).

4.15 Old Expander Proposal (98-157r0) [McGrath]

Jim McGrath started by saying that any change in the SCSI protocols "might"
break existing bus expanders.  The essence of Jim's proposal was an effort to
test the operation of a newly negotiated set of transfer parameters,
particularly double-edge clocking.  Jim described a testing method that would
rely on exchanging commands between the target and initiator, which met
resistance from the group.

Jim's preferred testing method used Data In and Data Out (what might be called
unsolicited Data In and Data Out, because they are not the result of a
command).  Data received by the initiator during a Data In phase would be
automatically repeated back to the target during the immediately subsequent
Data Out phase.  The group discussed the mechanics of the Data I/O method.

One addition to the proposal was requiring that the Data I/O testing be
bracketed by messages clearly showing when the testing starts and end.  The
number of bytes to be transferred during the Data I/O testing was discussed,
with options such as the REQ/ACK offset value or some other explicit value.
Jim agreed to prepare a specific proposal for the July meeting.

4.16 New Expander Proposal (98-158r0) [McGrath]

Jim presented a proposal that a new message byte precede the Identify message.
The new message would be distinguishable from the Identify because bit 7 would
be zero.  The low order nibble of the proposed new message would describe the
transfer properties of the I_T nexus that follows.  The information
communicated by the new message could be snooped by expanders to determine the
transfer properties of the I_T nexus, thus eliminating some amount of state
knowledge required in the bus expander.  The intent of the proposal was
providing bus expanders information about the transfer parameters of the data
phase(s) to follow in the current connection.

Concerns were raised about the new message breaking long-standing rules about
Identify messages coming first.  Alternatives were raised but not found
acceptable.  Questions were raised about the need for the capability, to which
Bill Galloway and Dave Steele answered that the capability definitely would be
required to identify the use of double-edge clocking.  The expander cannot
dynamically determine that double-edge clocking is being used and modify its
handling of the data signals fast enough.

The consensus was that a new message be defined to provide the results of a
transfer parameters negotiations to bus expanders.  Jim asked the group to
consider the consensus idea overnight and bring thoughts to the EPI portion of
the SCSI Working Group.  Based on the results of the SCSI Working Group, Jim
agreed to take responsibility for writing a new proposal reflecting the
opinions expressed the next day.

Chair's note:  Later in the week other proposals were presented for
communicating the use of double-clocking to bus expanders that seemed to have
better consensus. See items 4.2 and 7.2 in 98-147.

5.   Meeting Schedule

The next meetings of SPI-3 Working Group will be:
o    May 22, 1998 from 9 am to 5 pm hosted by Seagate in Chicago, IL at the
     O'Hare Hilton (773-686-8000),
o    June 19, 1998 from 9 am to 5 pm in Huntington Beach, CA hosted by QLogic
     at the Hilton Waterfront Hotel (714-960-7873), and
o    July 13, 1998 from 9 am to 8 pm in Portland, ME hosted by Digital
     Equipment Corp. at the Holiday Inn By the Bay (207-775-2311).

6.   Adjournment

The meeting was adjourned at 6:44 p.m. on Monday May 4, 1998.

John Lohmeyer                  Email: lohmeyer at ix.netcom.com
Symbios, Inc.                  Voice: +1-719-533-7560
4420 ArrowsWest Dr.              Fax: +1-719-533-7036
Colo Spgs, CO 80907              BBS: +1-719-533-7950

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