Death to I_T_L_Q nexus

George Penokie george.penokie at
Mon Jun 16 14:21:28 PDT 2014

Formatted message: <a href="">HTML-formatted message</a>

There are not very many cases where one plus the other wording is needed.
In most cases command identifier can be substituted for I_T_LQ nexus.
And yes this is an execution attempt.
Bye for now,
George Penokie
Avago Technologies
3033 41 St NW
Rochester , MN 55901
george.penokie at
On Wed, Jun 11, 2014 at 2:03 PM, Ralph Weber <Ralph.Weber at> wrote:
>  I would worry about 'I_T_L nexus plus command identifier' *only* if
> there are dozens of them. If use of the phrase can be limited to a handful
> of places, then 'I_T_L_Q nexus' has clearly fallen to the level of an
> almost useless term. In this regard, I am opposed to creating a new term
> just to have a term.
> My much less profound question of mine is whether this effort constitutes
> "executing I_T_L_Q nexuses'. Sorry, if only George gets this joke. It is
> based on a very old T10 food fight, but the fight was the basis for the
> requirement that commands be processed, not executed.
> All the best,
> .Ralph
>  ------------------------------
> *From:* owner-t10 at [owner-t10 at] on behalf of Kevin D Butt [
> kdbutt at]
> *Sent:* Wednesday, June 11, 2014 1:22 PM
> *To:* George Penokie
> *Cc:* owner-t10 at; T10 Reflector
> *Subject:* Re: Death to I_T_L_Q nexus
>  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 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
> From:        George Penokie <george.penokie at>
> To:	     T10 Reflector <t10 at>,
> Date:        06/11/2014 08:35 AM
> Subject:	  Death to I_T_L_Q nexus
> Sent by:	  <owner-t10 at>
> ------------------------------
> 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:
>    **
> <;
> Bye for now,
> George Penokie
> Avago Technologies
> 3033 41 St NW
> Rochester , MN 55901
> 507-328-9017
> *george.penokie at* <george.penokie at>

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