[T10] [T13] Another depop quirk

Joe Breher Joe.Breher at wdc.com
Fri Mar 31 12:47:23 PDT 2017


During today’s SAT-5 discussion, we covered these errata proposals. The group has improved my wording. I have submitted r1 revisions:

Title: Repurposing Depopulation errata - STARTING ELEMENT
Description: If no element matching criteria, STARTING ELEMENT specifies a lower bound

T13 PDF Document File Number: f17116r1
: http://www.t13.org/documents/UploadedDocuments//docs2017/f17116r1-Repurposing_Depopulation_errata_-_STARTING_ELEMENT.pdf

T10/17-067r1: http://www.t10.org/cgi-bin/ac.pl?t=d&f=17-067r1.pdf

Joe Breher
Storage Architecture Technologist
Standards Setting Organization
San Jose Research Center
Western Digital
+1 (478) 2-Breher
+1 (478) 227-3437


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On Mar 30, 2017, at 10:10 PM, Joe Breher <Joe.Breher at wdc.com<mailto:Joe.Breher at wdc.com>> wrote:

I have submitted proposals for an errata to repurposing depopulation to both T10 and T13:

Title: Repurposing Depopulation errata - STARTING ELEMENT
Description: If no element matching criteria, STARTING ELEMENT specifies a lower bound

T13 PDF Document File Number: f17116r0: http://www.t13.org/documents/UploadedDocuments//docs2017/f17116r0-Repurposing_Depopulation_errata_-_STARTING_ELEMENT.pdf

T10/17-067r0: http://www.t10.org/cgi-bin/ac.pl?t=d&f=17-067r0.pdf


Joe Breher
Storage Architecture Technologist
Standards Setting Organization
San Jose Research Center
Western Digital
+1 (478) 2-Breher
+1 (478) 227-3437


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On Mar 24, 2017, at 9:08 AM, Mark Carlson <Mark.Carlson at taec.toshiba.com<mailto:Mark.Carlson at taec.toshiba.com>> wrote:

Yes, I really don't like the idea of probing around for a valid starting element.

-- mark

On Mar 24, 2017, at 8:33 AM, Joe Breher <Joe.Breher at wdc.com<mailto:Joe.Breher at wdc.com>> wrote:

Gentlemen -

Early implementations have uncovered another wrinkle that requires fixing in Repurposing Depopulation.

>From sbc4r13:

A storage element is a type of physical element. Physical elements are associated with a unique element
identifier that is assigned by the device server. The element identifier shall be non-zero. The association of
element identifiers to physical elements shall persist through all events (e.g., across all resets) except
Microcode Change (see SAM-6). The association of element identifiers to physical elements may persist
through Microcode Change events.

As specified above, the ELEMENT IDENTIFIER is non-zero for all physical elements in the device. The initial proposal included a restriction that the element space be contiguous, but this was removed in committee deliberations.

As the ELEMENT IDENTIFIERS are at the discretion of the device, there is no a priori mechanism for the host to learn a ‘safe’ STARTING ELEMENT to specify for the GET PHYSICAL ELEMENT STATUS command. This makes the following requirement difficult:

The STARTING ELEMENT field specifies the element identifier of the first physical element addressed by this
command. If the specified starting element is invalid, then the device server shall terminate the command with
CHECK CONDITION status with the sense key set to ILLEGAL REQUEST and the additional sense code set
to INVALID FIELD IN CDB.

I think the proper way to fix the standard is to add a requirement that a starting element of zero shall be interpreted by the device as starting at the first valid element identifier (since the requirement to have all identifiers contiguous had been removed in committee deliberations as per above).

If all are in agreement, I will draft proposals for both T10 and T13 to allow a STARTING ELEMENT of zero to be interpreted as ‘start with the first valid element’.

Agreed?

Joe Breher
Storage Architecture Technologist
Standards Setting Organization
San Jose Research Center
Western Digital
+1 (478) 2-Breher
+1 (478) 227-3437


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