Fw: 96-277r1 - Proposed Change in QErr for SPC-2

Charles Monia 237-6757 monia at AM.SHRMSG.SHR.mts.dec.com
Thu Feb 27 08:14:42 PST 1997


* From the SCSI Reflector (scsi at symbios.com), posted by:
* Charles Monia 237-6757 <monia at AM.SHRMSG.SHR.mts.dec.com>
*
Hi Peter:

I'm not clear on what you disagree with.  In the following, you say:

| [making] QErr == 00b mandatory would REQUIRE that Basic queuing targets
| permit initiators to set QErr to this value.

Are you against "QErr = 00b" or against requiring that "Basic" devices provide
a choice of behaviors that includes this option?

As I read Ed's note, he is effectively proposing a change in the Basic queing
model which replaces QErr = 01b with QErr = 00b as the behavior **required** of
all devices.  I agree that adding choice adds complexity. However, I don't
think that's being proposed. Of course, a choice of behaviors could still be
allowed but not required.

Charles


| * From the SCSI Reflector (scsi at symbios.com), posted by:
| * PJohansson at aol.com
| *
| In a message dated 97-02-26 23:03:30 EST, gardner at acm.org (Edward A. Gardner)
| writes:
| 
| <<Given recent reflector traffic, today I would vote for QErr=00 being
| mandatory, with support for other QErr values being optional.  Doing nothing
| has to be simpler than aborting any or all commands (after all, it's the same
| action as when a command completes normally).  Single host systems can always
| issue a TARGET RESET.  And it seems to be the preference of multi-host
| systems.>>
| 
| I've extracted only this portion because I agree with the rest of what Ed has
| said.
| 
| This one paragraph stands in opposition, though. If I understand such things
| correctly, QErr == 00b mandatory would REQUIRE that Basic queuing targets
| permit initiators to set QErr to this value. This is not OK. SBP-2 was
| designed to support and implement the Basic queuing model. SBP-2 devices
| can't, don't or won't (pick your favorite verb) QErr == 00b. Basic queuing
 | was also intended to restrict optionality.
| 
| I am still in support of QErr == 01b (only the faulted initiator's task set
| is aborted) as a mandatory requirement for Basic queuing.
| 
| Incidentally, Ed, a very sincere "THANKS!" for doing all that research into
| our archives.
| 
| Regards,
| 
| Peter Johansson
| 
| Congruent Software, Inc.
| 3998 Whittle Avenue
| Oakland, CA  94602
| 
| (510) 531-5472
| (510) 531-2942 FAX
| 
| pjohansson at aol.com
| 
| *
| * For SCSI Reflector information, send a message with
| * 'info scsi' (no quotes) in the message body to majordomo at symbios.com
| 

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* Charles Monia, Storage Architecture Group                      *
* Digital Equipment Co.  Internet: charles.monia at shr.mts.dec.com *
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* Fax: (508) 841-6100                                            *
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