Key Issues in the SCSI-3 Primary Commands (SPC)

Ralph Weber -- VMS -- ZKO3-4/U14 weber at
Tue May 31 18:13:44 PDT 1994


To:       Membership of X3T10

From:     Ralph O. Weber
          Digital Equipment Corporation

Date:     May 13, 1994

Subject:  Key Issues in the SCSI-3 Primary Commands (SPC)

This document is a randomly selected list of SPC issues about
which I would like working group guidance.

The MODE SELECT(10) clause says, "Device servers that implement
the MODE SELECT(10) command shall also implement the MODE
SENSE(10) command."  The MODE SENSE(10) clause says, "If the MODE
SELECT(10) command is implement the MODE SENSE(10) command shall
be implemented."  Based on these statements, a devious target
designer could implement MODE SENSE(10) but not MODE SELECT(10). 
Such a target implementtion would be exceptionally nasty for most
host software.  Can I reverse the sense of statement in the MODE
SENSE(10) clause?

Is the standard INQUIRY data SftRe bit still applicable in
SCSI-3?  Is it protocol specific?

Is the standard INQUIRY data CmdQue bit still applicable in

The standard INQUIRY data Sync, WBus16, and WBus32 bits are
specific to SIP.  How should these bits be handled in the SPC? 
Should I create a protocol-specific field?  Or, should I just
leave the bits?  If I create a protocol specific field, does
SftRe somehow map to it too?

Is the following statement correct: "The sense data shall be
available if a Auto Contingent Allegiance condition exists for
the task set"?  Is task set a wide enough boundary for the ACA

There is a sentence describing the "progress indication"  sense-
key specific bytes that I do not understand.  The sentence is:
These fields only apply to the FORMAT UNIT command with the Immed
bit set to one.  Does this mean that the sense-key specific bytes
are valid only while the device server is processing a FORMAT
UNIT command?

In item e) under deferred errors, the following sentence worries
me: "If a deferred error occurs after a task has entered the
enabled state and the task completes successfully, the target may
choose to return the deferred error information after the
completion of the current command."  This seems to conflict with
the following previous statement: "If a task terminates with
CHECK CONDITION status and the subsequent sense data returns a
deferred error that task shall not have been executed."

How should the SPC say that the ILLEGAL REQUEST sense key can
indicate that an invalid IDENTIFY message was received?

Should ASC/ASCQ 2F/00 text be changed from, "COMMANDS CLEARED BY

In the Control mode page, is the DQue bit valid for SCSI-3?

I am having serious difficulty SAMinizing the definition of the
Disconnect-reconnect mode page.  I fear that if I do SAMinize,
the definitions will be imprecise to the point of uselessness.

I cannot see a way to put the full description of all the READ
ELEMENT STATUS parameter pages in the SPC without dropping the
whole medium changer device model in the SPC.  Help!!!

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