Question on SPC-4 rev. 18 Extended Inquiry VPD page

Gerry.Houlder at seagate.com Gerry.Houlder at seagate.com
Mon Jul 6 08:03:10 PDT 2009


* From the T10 Reflector (t10 at t10.org), posted by:
* Gerry.Houlder at seagate.com
*
I don't agree with all of your suggested changes.
WU_SUP and CRD_SUP seems clearly to be an indication of whether the WU and
CRD bits in WRITE LONG commands will be accepted and acted upon. Therefore
I think they should remain DS.
I agree that NV_SUP and V_SUP should remain DS.
PI_I_SUP and SPT relates to type or style of Protection Information that
the DS can support. In that sense it is the same as GRD_CHK, APP_CHK, and
REF_CHK. Obviously all of the options cannot be simultaneously supported
because of specification limitations but these limitations are enforced by
the DS. I think all are DS related and I think all should be treated the
same (i.e., either DS or LU).
I agree the CbCS should be a DS option.
I guess it will take some CAP discussion to resolve this. I will forward
this email to the reflector, that should be enough documentation to get
this subject on the CAP agenda.
	     Ralph Weber						   
	     <roweber at ieee.org						   
	     >								To 
	     Sent by:		       Gerry.Houlder at seagate.com	   
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	     Available		       Re: Question on SPC-4 rev. 18	   
				       Extended Inquiry VPD page	   
	     07/04/2009 09:27						   
	     AM 							   
Gerry,
My tally is:
LU - SPT
DS - GRD_CHK
DS - APP_CHK
DS - REF_CHK
DS - UASK_SUP
DS - GROUP_SUP
LU - PRIOR_SUP
LU - HEADSUP
LU - ORDSUP
LU - SIMPSUP
DS - WU_SUP
DS - CRD_SUP
DS - NV_SUP
DS - V_SUP
TD - LUICLR
LU - P_I_I_SUP
LU - CBCS
DS - MULTI I_T NEXUS MICROCODE DOWNLOAD
My conclusion is that:
+ anything which is *totally* related to command processing
ought to be DS (Device Server);
+ anything which requires something outside the device server
(e.g., media format capabilities) ought to be LU (Logical Unit)
-- N.B., queuing functions involve the Task Manager which is
outside the Device Server and thus rate the LU (Logical Unit)
nomenclature; and
+ LUICLR is correct as TD (Target Device) because it clearly
involves multiple logical units.
Viewed from this perspective:
+ WU_SUP and CRD_SUP ought to change from DS to LU since
write-uncorrectable-type functions may need media format
support;
+ NV_SUP and V_SUP might be better as LU (instead of DS),
but the wording specifically avoids saying that volatile
or non-volatile cache is present in the device, so I
think command processing is the key concept and DS is
the appropriate nomenclature; and
+ CBCS clearly ought to switch from LU to DS.
If you agree with these changes, I will mark them for
inclusion in the next SPC-4. Otherwise, I guess a CAP
discussion (of an appropriate proposal) is needed.
All the best,
.Ralph
Gerry.Houlder at seagate.com wrote:
> Hi Ralph,
>
> As I read down the descriptions of the various bits and fields that are
in
> the Extended Inquiry VPD page (clause 7.7.4) I note that most of the
> descriptions have wording like
>
> "... bit set to xx indicates that the device server ..."
>
> but two of the last three descriptions have wording like
>
> "...bit set to xx indicates that the logical unit ...".
>
> These seem like examples of use of the "logical unit" term when "device
> server" should be the correct term. I think Mark Evans in particular has
> been a proponent of using device server in these situations. Can you make
> this as an editorial change? This seems to be the kind of thing that
would
> get fixed at an editor's meeting (if there was one).
>
>
>
>
>
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