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- Date: May 10, 1990
-
- To: X3T9.2 Membership
- From: Lawrence J. Lamers, X3T9.2 Secretary
- John B. Lohmeyer, X3T9.2 Chairman
-
- Subject: May 8-9, 1990 X3T9.2 Working Group Meeting
-
- John Lohmeyer called the meeting to order at 9:00 am, Tuesday, May 8, 1990.
- He thanked Peter Blackford of Astro Cable Company for hosting the meeting and
- he also thanked Nan-Max Travel for arranging the meeting. John also announced
- that Pat and George Penokie have a new son, Eric Joseph Penokie, born Tuesday,
- May 1, 1990. John congratulated the new father and thanked Pat for allowing
- George to travel so soon.
-
- As is customary, the people attending introduced themselves. A copy of the of
- the X3T9.2 membership list was circulated for attendance and corrections.
- Copies of the draft agenda and the recent document register were made
- available to those attending. Information on X3T9.2 and Mailing Subscription
- Forms were made available.
-
- The final agenda was as follows:
-
- 1. Caching Proposal (90-021R1) [Milligan]
- 2. Diagnostic Command Set (90-022) [Pickford] {Wednesday a.m.}
- 3. Packetized SCSI (89-130R1) [Stephens] {Tuesday}
- 4. Multi-ported SCSI (89-133R1) [Stephens] {Tuesday}
- 5. SCSI-3 document structure [Lamers]
- 6. 16/32-bit cable issues (90-48R1) [Penokie]
- 7. Initiator control of reconnection (90-62) [Lohmeyer]
- 8. RESERVE command conflict with the direct-access model.
- (90-059R0) [Penokie]
- 9. Interaction on LOG SELECT TSD and DS bits (90-067) [Milligan]
- 10. Report on the Cable Working Group (90-078) [Lamers]
- 11. Write protect editorial error (90-070) [Snively]
- 12. Reduced common-mode range on differential SCSI [Jessen]
- 13. ESDI Editorial Clarifications (90-74) [Lamers]
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- The following people attended the meeting:
-
- Name Status Organization
- ------------------------------ ------ ------------------------------
- Mr. Denis D. Springer O 3M Company
- Mr. Charles Brill P AMP, Inc.
- Mr. Ed Young O Archive Corp.
- Mr. Thomas Debiec O Belden Wire & Cable
- Mr. Thomas Wicklund P Ciprico Inc.
- Mr. Douglas Hagerman A Digital Equipment Corp.
- Mr. Rudy Stalzer A Digital Equipment Corp.
- Mr. Michael Carreira V Digital Equipment Corp.
- Mr. Fred Zayas V Digital Equipment Corp.
- Mr. I. Dal Allan P ENDL
- Mr. Kenneth Post P Future Domain
- Mr. Kurt Chan P Hewlett Packard Co.
- Mr. Mike Peper A Hewlett Packard Co.
- Mr. George Penokie P IBM Corp.
- Mr. Gary R. Stephens A IBM Corp.
- Mr. David A. Buesing O IBM Corp.
- Mr. Lawrence J. Lamers P Maxtor Corp.
- Mr. John Lohmeyer P NCR Corp.
- Mr. John Emerson O Prime Computer
- Mr. Gene Milligan A Seagate Technology
- Mr. Robert N. Snively P Sun Microsystems, Inc.
- Mr. D. W. Spence P Texas Instruments
- Mr. Peter Dougherty P UNISYS
- Mr. Doug Pickford A Western Digital
- Mr. Erik Jessen O Western Digital
-
- 25 People Present
-
- Status Key: P Principal
- A Alternate
- O Observer
- S Special Interest (frequent visitor)
- V Visitor
-
- The following new documents were distributed at the meeting:
-
- Document Doc Date Author Description of Document
- ------------- -------- ------------- ---------------------------------------
- X3T9.2/90-59 4/5/90 G. Penokie RESERVE command conflicts with
- Direct-Access Model
- X3T9.2/90-62 5/4/90 J. Lohmeyer Initiator Control of Reselection Order
- Rev 1
- X3T9.2/90-67 4/10/90 G. Milligan Interaction on LOG SELECT TSD and DS
- bits
- X3T9.2/90-70 5/3/90 R. Snively Editorial Error in SCSI-2 Rev 10C about
- Write Protect
- X3T9.2/90-71 5/7/90 T. Wicklund Issues involved with RAID-3 disk arrays
- using SCSI drives
- X3T9.2/90-73 5/3/90 R. Snively Proposed Structure for SCSI-3
- Documentation
- X3T9.2/90-74 5/5/90 L. Lamers Request for ESDI Editorial Clarifications
-
- Results of meeting
-
- 1. Caching Proposal (90-021R1) [Milligan]
-
- Gene Milligan's revision 1 proposal was discussed. Several preferences
- were expressed:
-
- * The function of controlling suppression of the MODIFY DATA POINTERS
- message more properly belongs in the Control Mode page.
-
- * Tom Wicklund recommended that more command-by-command caching controls
- should be provided beyond just the DPO and FUA bits.
-
- * Larry Lamers recommended that a method be included to switch the
- caching algorithm.
-
- Regarding the first point above, Dal and Larry suggested that a mode page
- be defined enable/disable all messages.
-
- Larry Lamers objected to the "ascending, contiguous, sequential order" in
- Forced Sequential Write (FSW) bit description because some defect management
- schemes may preclude this. It was agreed to drop the "contiguous,
- sequential order" part.
-
- Control of the MODIFY DATA POINTER message will be removed from the FSW bit.
- The Forced Sequential Read (FSR) bit will be deleted since it is no longer
- relevant.
-
- Gary Stephens asked does FSW imply a write-through? The consensus was that
- it does not; write-through is controlled by FUA. FSW applies on a per I/O
- process basis.
-
- Gene accepted an action item to revise his proposal and develop another MODE
- SELECT page or extension to an existing page to enable/disable messages.
-
- 2. Diagnostic Command Set (90-022) [Pickford] {Wednesday a.m.}
-
- Doug Pickford gave a presentation entitled "Jumbo Shrimp"; which is an
- oxymoron like "SCSI Diagnostics". Doug is still requesting feedback so that
- he can develop a new proposal that answers the prior objections while
- offering the functionality needed to diagnose the underlying hardware. Doug
- presented the structure for the proposed document and stated that the
- diagnostics are aimed at rigid disk drives and not at other device types.
-
- Dal announced that FlexStar (Mike Witte, VP Marketing, 408-433-0770) has
- started an industry group that will meet at Spring Comdex to standardized
- testing of the physical disk drive within SCSI direct-access devices. Phil
- Devin of DataQuest is also supporting this effort.
-
- Doug plans to develop a new proposal for consideration at the next working
- group meeting.
-
-
-
- 3. Packetized SCSI (89-130R1) [Stephens] {Tuesday}
-
- Discussion on this was brief as Gary has given several previous
- presentations on packetized SCSI. There were no new questions. The
- performance improvement potential was extolled by several participants.
-
- 4. Multi-ported SCSI (89-133R1) [Stephens] {Tuesday}
-
- There was extensive discussion on this topic (about 3 hours). Much time was
- spent on understanding the concept of grouping.
-
- Two terms were defined as follows:
-
- A multiple path process allows an initiator to choose one of several
- paths for an initial connection and the target shall complete the I/O
- process on the same path.
-
- A dynamic path process allows an initiator to choose any path for an
- initial connection and the target to choose any path at each reconnection
- for the I/O process.
-
- Gary objected to these terms because his proposal is more general. Each
- port on a device may be given a name. Ports with the same name belong to
- the same group. I/O processes may use any port with the same group name.
-
- Once the concept of completing an I/O process on more than one port is
- introduced, then it is necessary to add some means to uniquely identify I/O
- processes across multiple ports. Queue tags are not sufficient.
-
- While most people agreed that multiple porting should be added to SCSI-3,
- many expressed concern that Gary's proposal may go too far. Dal questioned
- whether the SCSI market really needs or wants the full capabilities (and
- complexity) associated with dynamic pathing (group size greater than one).
- IPI has a 40-page working document devoted to this topic.
-
- After several hours of discussion, Gary asked if we could now review his
- document. A number of minor changes were identified and Gary agreed to
- prepare a revision 2.
-
- 5. SCSI-3 document structure [Lamers]
-
- Bob Snively gave an introduction to his view of SCSI-3 document structuring
- (90-073). He identified three documents:
-
- SCSI-3E: An evolutionary document containing multi-port, P&L cables,
- alternate drivers (a small-swing differential), aperture card
- scanner commands, revised MODE SELECT pages, any new messages
- needed, the diagnostic command set, and any further ideas that
- are evolutionary in nature. This document would not replace the
- SCSI-2 standard; it would contain supplemental information.
-
- SCSI-3P: A more revolutionary document which may not be backwards
- compatible with SCSI-2 or SCSI-3E. It would contain multi-
- pathing, packetizing, and other revolutionary concepts.
-
- SCSI-3FC: This document would contain the necessary information to use
- SCSI commands over the Fiber Channel. It would include the
- frame definitions including headers.
-
- John Lohmeyer stated that in his opinion these are the possible future
- markets for SCSI and do necessarily reflect how the documents should be
- structured.
-
- Larry Lamers described his approach to SCSI-3. He is interested in doing an
- evolutionary document that would supersede the physical sections of SCSI-2,
- but not affect the later sections. Products complying to the new document
- would use its physical sections plus the SCSI-2 command sets. He hopes this
- document could be completed in 12-15 months and expects that it would
- include the new P/L cables and improved specifications on cable electrical
- characteristics. It may also include multiple ports, alternative drivers
- and receivers, and nexus in/out phases.
-
- He said he needs more time to think about the best way to structure the
- other portions of the SCSI-3 standard.
-
- John stated that if the committee is in agreement on beginning a SCSI-3
- physical layer document then the project proposal should be drafted.
-
- 6. 16/32-bit cable issues (90-48R1) [Penokie]
-
- Dal Allan reported that Jean Kodama has questioned magnitude of the skew
- factors on 16- and 32-bit cables. John Lohmeyer said that some NCR chip
- engineers have also expressed concern over whether mixing 8-bit and 16-bit
- cables will result in skewed signals due to differences in cable length.
- John said his (sometimes flawed) intuition on transmission lines is that the
- cable length difference should not matter as long as the lines are properly
- terminated. Everyone agreed that testing is necessary.
-
- Tom Wicklund volunteered to help, noting that it should be possible to
- modify the Ciprico SCSI-2 host adapter A/B cable host adapter to use a 16-
- bit cable.
-
- Dal stated that the timing budgets must be defined clearly enough to insure
- interoperability.
-
- Ken Post pointed out that George's document had dropped the requirement to
- ground reserved lines at the terminators. George will revise his document
- to say that reserved lines shall be grounded at the terminator and open
- elsewhere.
-
- 7. Initiator control of reconnection (90-62) [Lohmeyer]
-
- Tom Wicklund gave a presentation on his paper (90-071) about RAID-3 disk
- arrays. The presentation supported the NCR request for the messages to
- provide initiator control of reselection.
-
- Tom pointed out that SCSI disk drives are nearly equal in cost to ESDI
- drives and the array controller interface logic is much less complex (2
- chips for SCSI vs. 30 chips for ESDI). However, the integrator does not
- have control of the read-ahead and reconnection. Control of reselection
- would dramatically reduce the size of the buffer needed for the RAID
- controller.
-
- Dal noted that the need for initiator control of reselection has come up in
- the past. Dave Buesing of IBM could probably have avoided his need for a
- special arbitration algorithm had these messages been available.
-
- Tom Wicklund stated that in doing a fiber channel physical layer these
- messages would be useful in managing the devices attached to the fiber
- channel controller.
-
- The DO NOT CALL ME (a.k.a. INITIATOR RECONNECTION REQUEST) was renamed
- to DISABLE TARGET RECONNECTION. After some additional discussion, Bob
- Snively suggested that it might be better to only disable target
- reconnections for data transfers. This would permit a target to reconnect
- and immediately disconnect when the data is ready for transfer.
-
- John Lohmeyer accepted an action item to revise his proposal for the next
- meeting.
-
- 8. RESERVE command conflict with the direct-access model.
- (90-059R0) [Penokie]
-
- John reviewed the conflict and reported on his research into prior minutes.
- The minutes said that reservations and prevention of medium removal are
- independent concepts. However, the minutes shed no additional light on what
- was really meant by "independent". Larry continued to maintain that
- independent only meant that prevention of medium removal does not imply an
- automatic reservation. PREVENT ALLOW MEDIUM REMOVAL commands with a prevent
- bit of zero are allowed through reservations to avoid deadlock conditions.
- If such commands with a prevent bit of one were also allowed through
- reservations, then deadlocks could occur.
-
- Paul Boulay had registered his opinion on the subject via a message on the
- SCSI BBS which John read. He supported Larry's position and George Penokie
- also joined their position.
-
- Those opposing this position mostly disliked the fact that one must check
- the prevent bit before deciding whether a PREVENT ALLOW MEDIUM REMOVAL
- command may be accepted or rejected when a reservation is active. They
- interpreted "independent" as meaning both flavors of the command should be
- executed in spite of a reservation to another device.
-
- The new fathers gradually won over most of the opposition and Larry accepted
- an action item to draft wording for a motion at the next plenary meeting.
-
- 9. Interaction on LOG SELECT TSD and DS bits (90-067) [Milligan]
-
- Gene Milligan accepted an action item to develop a motion that will resolve
- the conflict in LOG SELECT and LOG SENSE through selective surgery. That
- is, excising the last two sentences of paragraph 13 of section 7.3.2.
-
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- 10. Report on the Cable Working Group (90-078) [Lamers]
-
- See X3T9.2/90-078 for minutes of the meeting. In a nutshell, several cable
- vendors have completed the initial testing, the cross talk measurements
- require correlation which Jim Fiala of 3M is undertaking, a second iteration
- on the cable testing will be done based on the initial results, and the next
- cable meeting is set for Tuesday, June 19, 1990 at 1:00 p.m.
-
- An ad-hoc meeting on connectivity issues is planned for Tuesday, June 19,
- 1990, at 10:00 a.m. The purpose of this meeting is to address the issue of
- how to use high-density connectors in assembling systems. Connector, cable,
- cable assembly, and system vendors are invited to demonstrate their
- solutions.
-
- 11. Write protect editorial error (90-070) [Snively]
-
- The definition of the write protect (WP) bit in the device specific
- parameter byte in MODE SENSE data is not consistent in sections 8, 9, and
- 15. There was a short discussion, however prior to a final agreement
- several members need to consult with the folks back home.
-
- Based on the original wording in SCSI-1 the WP bit is reserved in the MODE
- SELECT data and an indicator of the write protect condition in MODE SENSE.
-
- Larry Lamers accepted an action item to draft wording to sychronize the
- wording of the WP bit in sections 8, 9, and 15. The wording will be based
- on the input from HP, Seagate, Sun, and Maxtor. The draft wording is in
- preparation for a motion at the next plenary meeting.
-
- 12. Reduced common-mode range on differential SCSI [Jessen]
-
- Erik Jessen questioned why SCSI-2 specifies +12/-7 volt common-mode range on
- differential drivers/receivers. If SCSI really experiences its specified
- range significant currents would flow through the ground wires.
-
- He pointed out that HiPPI uses a 1 volt range on 10 mA ECL drivers.
- However, HiPPI is only point to point. IPI has 25Mhz ECL but it is not
- multi-drop, only point to point.
-
- There were hopes that reducing this range and reducing the voltage swing
- could result in a differential drive option which could be integrated into
- one or two chips. Eric Jessen accepted an action item to investigate
- reduced differential common-mode range and the cable requirements.
-
- 13. ESDI Editorial Clarifications (90-74) [Lamers]
-
- Larry said that Maxtor had found several editorial issues with ESDI. He had
- discussed these with Dal and Tom Wicklund. He plans to review the issues
- with other ESDI-interested parties prior to the June plenary meeting and
- expects to make a motion directing the technical editor to make some
- editorial clarifications during the final editing.
-
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- Review of action items
-
- 1) Larry Lamers will draft wording to sychronize the wording of the WP bit
- in sections 8, 9, and 15.
-
- 2) Larry Lamers will draft wording for resolving the RESERVE command
- conflict with the direct-access model.
-
- 3) John Lohmeyer will revise his proposal for initiator control of
- reconnection.
-
- 4) Eric Jessen will investigate reduced differential common-mode range and
- the cable requirements.
-
- 5) Doug Pickford will develop a new proposal on diagnostics for
- consideration at the next working group meeting.
-
- 6) Gary Stephens will revise the multi-ported SCSI proposal to incorporate
- the results of the discussion at May working group meeting.
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