Fw: Letter ballot comments on THRESHOLD EXPONENT field

Kevin D Butt kdbutt at us.ibm.com
Tue Aug 20 10:21:01 PDT 2013

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IBM does not accept this revision to SBC-3.  See below for the reasoning.
Kevin D. Butt
SCSI Architect, Tape Firmware, T10 Standards
Data Protection & Retention
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com
----- Forwarded by Kevin D Butt/Tucson/IBM on 08/20/2013 10:19 AM -----
From:	Roger Hathorn/Tucson/IBM
To:	Kevin D Butt/Tucson/IBM at IBMUS, 
Date:	08/19/2013 06:20 PM
Subject:	Re: Fw: Letter ballot comments on THRESHOLD EXPONENT field
I completely disagree with this statement:
"A threshold exponent field set to a non-zero value indicates the logical 
unit supports logical block provisioning thresholds (see"
That is a change to the current definition and adds a normative 
requirement that  if I support resource counts in the LBP log page, then I 
shall also  support logical block provisioning thresholds, which also 
states that I have to support the logical block provisioning mode page. 
I am OK with saying "A threshold exponent field set to zero indicates that 
the logical unit does not support logical block provisioning thresholds.", 
because that is already in the draft.	 I am not OK with the inverse. 
This is the main reason for my comment that was rejected: 
The threshold exponent is also used for expressing available and used 
resource counts in the LBP log page.  One could support providing of the 
log page resource counts without supporting LBP thresholds. 
The response was: 
"No change - The one usage of threshold exponent in the LBP log page 
references back to this VPD page and now has modified wording to make the 
i.e, clearer (see SBC-3 revision 35f or later). The threshold exponent 
referenced in the LBP log page is also the same threshold exponent defined 
in the VPD page. If the contents of the THRESHOLD EXPONENT field are 
non-zero then the device supports these thresholds. It is not just implied 
it is stated as such in the text."
The content of the LPB log page does not contain thresholds, it contains 
resource counts. They are useable without supporting thresholds.  I don't 
see where it is stated anywhere in the letter ballot version of the text. 
Feel free to forward this response. 
Roger G. Hathorn
STSM, Storage Systems Development
IBM Systems and Technology Group

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