98-115r2 - Sundry Minor Enhancements for SPC-2

ROWEBER at acm.org ROWEBER at acm.org
Sat Mar 14 10:57:32 PST 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* ROWEBER at acm.org
*
Sundry Minor Enhancements for SPC-2

My apologizes to everybody for not getting this out earlier.  This
revision accepts comments received from Digital and Seagate.  The
Digital comment is accepted by including the proposed revision of the
note, minus the last sentence and with 'shall' changed to 'should'.
The Seagate comment is accepted by deleting the word 'individually'
|from the proposed text (a change indicated by strikeout text).

During the past several months various suggestions have been made for
minor enhancements in SPC-2.  These proposals are complied here for
consideration by T10.

1) Add the following before the last sentence in clause 4.2.4:

    "If the information being transferred to the data-in buffer
    includes fields containing counts of the number of bytes in some
    or all of the data, the contents of these fields shall not be
    altered to reflect the truncation, if any, that results from an
    insufficient allocation length value, unless the standard that
    describes the data-in buffer format specifically states
    otherwise."

It has been noted that most command descriptions include wording with
effects similar to what is proposed above.  However, some command
descriptions are silent on this subject and adding the proposed
wording in clause 4.2.4 (the description of the allocation length CDB
field) will cover all cases.

2) In the process of resolving an issue regarding field pointer bytes
sense-key specific data in the standard sense data (see 97-187), the
working group produced the following statement of its position
regarding multi-byte fields:

    a) A multi-byte field is a defined field in a CDB or parameter
       list whose length exceeds one byte; and
    b) The contents of the sense-key specific data for the ILLEGAL
       REQUEST sense key is not specified by SCSI-2 when the error
       occurs in a reserved field.

The following should be added at the end of the third paragraph after
Table 63 in clause 7.20.1 to embody the committee's position in
SPC-2:

    "If a field whose length exceeds one byte is reserved, it shall
    be treated as a multiple-byte field.  If several consecutive
    bytes are xxxxxxxxxxxx reserved, each shall be treated as a
    single-byte field."

3) It has been noted that no SCSI standard contains the requirement
that invalid operation codes result in a CHECK CONDITION status.  To
address this omission, the following wording should be added at the
end of the second paragraph in clause 4.2:

    "If a device server receives a CDB containing an operation code
    that is invalid or not supported, it shall return CHECK CONDITION
    status with the sense key set to ILLEGAL REQUEST and an
    additional sense code of INVALID COMMAND OPERATION CODE."

4) The SPC recommendations for  virtual units regarding the contents
of the device identification VPD page have been overtaken by events,
specifically the IEEE Tutorial for SCSI use of IEEE company_id (also
available as T10/97-101r2).  Therefore, it is proposed that note 53
be replaced with:

    "Note 53  In the case of virtual logical units (e.g., volume sets
    as defined by SCC), the Identifier field (see table 111) should
    be an IEEE Registered Extended name.  The IEEE Registered
    Extended name should have a code of 3h in the Identifier type
    field and an NAA value of 0110b as defined in FC-PH."

The normative references clause needs to be reviewed and updated with
respect to FC-PH and the acronyms clause needs to have FC-PH added. 

5) The description of the Identification descriptor field in the
device identification VPD page has been rendered incorrect by the
addition of the Association field.  The second paragraph before Table
112 in clause 8.4.3 should be replaced with:

    "Each Identification descriptor (see table 111) contains
    information identifying the logical unit, physical device, or
    access path used by the command and returned parameter data.  The
    Association field indicates the entity that the Identification
    descriptor describes.  If a physical or logical device returns an
    Identification descriptor with  the Association field set to 0h,
    it shall return the same descriptor when it is accessed through
    any other path."
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