Questions Regarding the SES Specification

Hamel, Mark Mark.W.Hamel at
Tue May 2 12:43:24 PDT 2000

* From the T10 Reflector (t10 at, posted by:
* "Hamel, Mark" <Mark.W.Hamel at>
	While reviewing the "SES, SCSI-3 Enclosure Services Command Set,
(SES), REV 8b" document, there appears to be some apparent inconsistencies
on some items that I would appreciate some input on, as well as some
clarification on other items:

> *	In Annex A, Table A.2, pages 68 and 69, the PRODUCT REVISION LEVEL
> field of the Primary sub-enclosure descriptor occupies bytes 44-47; this
> is a 4-byte field.  However, this same field for all of the other
> sub-enclosures in the table is documented as an 8-byte field.  Further,
> the same field is described in section 6.1.1 as a 4-byte field.  This
> seems inconsistent.  Is there a specific reason why the fields are of
> different lengths?
> *	In the description of the Element descriptor page in section 6.1.11,
> Table 18 on page 32 shows the DESCRIPTOR LENGTH field to be arranged in
> Little Endian order.  In other SCSI specifications, multiple byte fields
> are arranged in Big Endian order. Is this a typo? If not, is there a
> specific reason why this is in Little Endian order?
> *	In section A.3, in the sixth paragraph on page 70 labeled TYPE
> DESCRIPTOR HEADER:, the fourth sentence reads:  "All those elements
> defining SCSI devices shall be listed before elements of other types,
> regardless of sub-enclosure identification."  Does anyone recall why this
> rule was added??  
		It seems that an additional pass over the incoming data is
needed to satisfy this requirement.  

> *	In section 6.1.1, in the seventh paragraph on page 17 labeled
> SUB-ENCLOSURE IDENTIFIER:, a primary sub-enclosure is defined.  Does this
> definition apply to sub-enclosure reporting as defined in Annex A?
> Specifically, must the primary's sub-enclosure identifier be zero?  This
> may create fail-over problems for the user of an SES device if the primary
> must be sub-enclosure zero.  
	I would appreciate anyone's comments on these. Thanks.

Best Regards:
Mark Hamel
Compaq Computer Corporation
Advanced Technology Group
Storage Products Division
Tel # (508) 841-2653
Fax # (508) 841-2556
e-mail: mark.w.hamel at

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