Death to I_T_L_Q nexus

George Penokie george.penokie at avagotech.com
Mon Jun 16 14:19:07 PDT 2014


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1406160_f.htm">HTML-formatted message</a>

Kevin,
There are not many places that would need the phrase :I_T_L nexus plus
command identifier'. In many cases the term I_T_L_Q nexus is really only
the command identifier when looked at in context with where it is being
used.
There is noway I am going to define a term for :I_T_L nexus plus command
identifier', the whole point of this exercise is to "execute" the entire
idea that those two terms are linked together.
Bye for now,
George Penokie
Avago Technologies
3033 41 St NW
Rochester , MN 55901
507-328-9017
george.penokie at avagotech.com
On Wed, Jun 11, 2014 at 1:22 PM, Kevin D Butt <kdbutt at us.ibm.com> wrote:
> George,
>
> I have no objections with the concept of this direction. I was initially
> concerned with the terminology used since FCP-4 also used the term.
>  However, upon further review this seems to fall right into place.
>
> FCP-4 Terms:
> *Command Identifier* = 3.1.7 command identifier: The information that
> uniquely identifies a command. See Annex A and SAM-5.  This is synonymous
> with OX_ID (Note that If retransmission is enabled, the task retry
> identifier is also used to construct the command identifier.)
>
> I do have a concern with using "I_T_L nexus plus command identifier"
> throughout all the standards.  I would prefer we come up with a term to
> describe this.  Perhaps something like "Fully qualified command
> identifier".	I know that doesn't really save words or letters when typing
> it, but it does better convey, I think, the concept for which it is used.
>
> Annex terminology mapping seems to have inconsistencies in it.
> For SAM-3 command identifier = task tag
> For SAM-4 command identifier = I_T_L_Q nexus
>
> I think, perhaps for SAM-4 mapping it should be "I_T_L nexus plus command
> identifier = I_T_L_Q nexus"
>
> Also, there is a typo of "poert" instead of "port" in 4.6.5.1 in the SCSI
> Initiator Port box
>
> Thanks,
>
> 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
> http://www-03.ibm.com/servers/storage/
>
>
>
> From:        George Penokie <george.penokie at avagotech.com>
> To:	     T10 Reflector <t10 at t10.org>,
> Date:        06/11/2014 08:35 AM
> Subject:	  Death to I_T_L_Q nexus
> Sent by:	  <owner-t10 at t10.org>
> ------------------------------
>
>
>
> If don't reached SAM overload yet this proposal should push you over the
> edge. Here is the overview:
>
> There has been a long standing problem with the I_T_L_Q nexus as it
> combines routing information with a command identifier. The routing part is
> the I, the T, and the L. The command identifier is the Q. In addition the
> nexus really does not have a satisfactory home in the SAM-5 UML model.
>
> This proposal solves the UML issue by adding a Management Application
> Client class that is a “kind of” Application Client class. The new
> Management Application Client class has I_T Nexus Identifier attributes and
> I_T_L Nexus Identifier attributes. The Management Application Client class
> is the class that goes out and finds all the nexuses in the SCSI domain.
> The method used for the Management Client class to do this is protocol
> specific. For example in SAS the discovery is defined in the SPL standard.
>
> This also separates Q from nexus and replaces that with a standard alone
> attribute called a Command Identifier attribute. The effect of this is that
> all the I_T_L_Q nexus terms will be replaced with either Command Identifier
> or I_T_L nexus and command identifier. This causes extensive changes to
> several standards but has the largest effect on SPL, then SAM, then SPC,
> and finally SBC. To prevent issues with existing published standards the
> term I_T_L_Q nexus will have to remain but it will be defined as being
> synonymous with I_T_L nexus plus command identifier.
>
> Your request to upload a file or files to the T10 site has been accepted.
>
> Your PDF file will be posted at:
>
>    *http://www.t10.org/cgi-bin/ac.pl?t=d&f=14-155r0.pdf*
> <http://www.t10.org/cgi-bin/ac.pl?t=d&f=14-155r0.pdf&gt;
>
> Bye for now,
> George Penokie
>
> Avago Technologies
> 3033 41 St NW
> Rochester , MN 55901
>
> 507-328-9017
> *george.penokie at avagotech.com* <george.penokie at avagotech.com>
>



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