data protection format types

Gerry.Houlder at seagate.com Gerry.Houlder at seagate.com
Thu Aug 10 14:46:28 PDT 2006


* From the T10 Reflector (t10 at t10.org), posted by:
* Gerry.Houlder at seagate.com
*
These three bits, as well as the other bits in the extended Inquiry VPD
page, are set by the target device depending on its capability. In the case
of these three bits, the target indicates whether it is capable of checking
the Guard field, the Application Tag field, and the Reference Tag field
(respectively) when the target is configured to use protection information.
The settings have a bearing on the values in the WRPROTECT, RDPROTECT, and
VPROTECT fields that the drive will accept.
 For example: if GRD_CHK=1, APP_CHK=0, and REF_CHK=1; if the RDPROTECT
field is set to 001b in a read command then the Guard field and Reference
Tag field will be checked but the Application Tag field will not. If the
target had reported APP_CHK=1 instead of zero, then the target is promising
to check the application tag field as well when the RDPROTECT field is set
to 001b. See the RDPROTECT field table in SBC-3 for an exhaustive list of
the cases.
These three bits are not really tied to the format type. They apply equally
well to types 1 and 2. Type 3 describes the use of the 8 bytes of
protection information as being vendor specific, so the three fields are no
longer defined. This kind of makes the GRD_CHECK, et. al. bits meaningless
for type 3.
	     Gary.Franco at emule						   
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								   Subject 
				       data protection format types	   
	     08/10/2006 02:46						   
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I have a question with regard to the discussion in SPC4r04
In clause 7.6.4 Extended INQUIRY Data VPD page, there are 3 bits discussed
      GRD_CHK,
      APP_CHK and
      REF_CHK
They are defined as far as their meaning, but never discussed how they are
set.
Is this part of the format process, or simply the capability of the device
firmware or design?
I got a response that said go look at any protected command (i.e.
read/write, etc.), however that does not answer the question.
Are these 3 bits somehow tied to the format type (type 1, 2, or 3)
__________________________________
Gary Franco Consultant Engineer
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