Subject: Re: iSCSI: v15 R2T and DATA-OUT

From: "Julian Satran" <[email-masked]>
Date: Thu, 25 Jul 2002 00:59:34 +0300

There is no TTT for data-In. Julo

                      "Rod Harrison"                                                                                                        
                      <rod.harrison@win        To:       <[email-masked]>                                                                  
                      driver.com>              cc:                                                                                          
                      Sent by:                 Subject:  iSCSI: v15 R2T and DATA-OUT                                                        
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                      .edu                                                                                                                  

                      07/24/2002 10:24                                                                                                      
                      PM                                                                                                                    

Folks,

             There is a potential inconsistency in the description of the
use of
the LUN field in DATA-OUT and R2T in the working v15 draft.

             9.7.3 Target Transfer Tag, for DATA-IN last paragraph says ...

             "If the Target Transfer Tag is provided, then the LUN field
MUST hold
a valid value and be consistent with whatever was specified with the
command;"

             9.8.5 Target Transfer Tag, for R2T says ...

             "The Target Transfer Tag and LUN are copied in the outgoing
data PDUs
and are used by the target only."

             Potentially a target could return a different LUN field in the
R2T,
for perhaps some funky LUN mapping or other internal reason expecting
it to be copied to the DATA-OUT as per the R2T text. I suspect we just
want to say this is not allowed and the LUN field MUST be the same as
the command PDU.

             Either way I think we need to indicate what is expected of the
initiator if the LUN field in the R2T does not match the LUN in the
command PDU.

             Apologies for not spotting this before the end of last call.

             - Rod

---

From: "Rod Harrison" <[email-masked]>
Date: Wed, 24 Jul 2002 20:57:05 -0500

Oops, I see the confusion. I said DATA-IN in my message when I meant
DATA-OUT.

	However, re-reading the section of v15 in question I now see that the
third paragraph is referring to the DATA-IN LUN, not the DATA-OUT LUN.
That wasn't clear to me when first scanned it because of the paragraph
break.

	Perhaps a note of clarification needs to be added?

	- Rod

-----Original Message-----
From: Rod Harrison [mailto:[email-masked]]
Sent: Wednesday, July 24, 2002 8:51 PM
To: Julian Satran
Cc: [email-masked]
Subject: RE: iSCSI: v15 R2T and DATA-OUT

Julian,

	I think you've misread my message. I was questioning how the
initiator should handle the LUN between an R2T and the DATA-OUT(s)
that satisfy it.

	DATA-OUT says copy the LUN from the command PDU, R2T says copy the
LUN from the R2T to the DATA-OUT. Which is correct if the R2T contains
a different LUN than that in the command PDU?

	- Rod

-----Original Message-----
From: Julian Satran [mailto:[email-masked]]
Sent: Wednesday, July 24, 2002 5:00 PM
To: Rod Harrison
Cc: [email-masked]; [email-masked]
Subject: Re: iSCSI: v15 R2T and DATA-OUT

                      "Rod Harrison"
                      <rod.harrison@win        To:
<[email-masked]>
                      driver.com>              cc:
                      Sent by:                 Subject:  iSCSI: v15
R2T and DATA-OUT
                      [email-masked]
                      .edu

                      07/24/2002 10:24
                      PM

Folks,

             There is a potential inconsistency in the description of
the
use of
the LUN field in DATA-OUT and R2T in the working v15 draft.

             9.7.3 Target Transfer Tag, for DATA-IN last paragraph
says ...

             "If the Target Transfer Tag is provided, then the LUN
field
MUST hold
a valid value and be consistent with whatever was specified with the
command;"

             "The Target Transfer Tag and LUN are copied in the
outgoing
data PDUs
and are used by the target only."

             Potentially a target could return a different LUN field
in the
R2T,
for perhaps some funky LUN mapping or other internal reason expecting
it to be copied to the DATA-OUT as per the R2T text. I suspect we just
want to say this is not allowed and the LUN field MUST be the same as
the command PDU.

             Either way I think we need to indicate what is expected
of the
initiator if the LUN field in the R2T does not match the LUN in the
command PDU.

             Apologies for not spotting this before the end of last
call.

             - Rod

---

From: "Rod Harrison" <[email-masked]>
Date: Wed, 24 Jul 2002 20:51:19 -0500

Julian,

	- Rod

-----Original Message-----
From: Julian Satran [mailto:[email-masked]]
Sent: Wednesday, July 24, 2002 5:00 PM
To: Rod Harrison
Cc: [email-masked]; [email-masked]
Subject: Re: iSCSI: v15 R2T and DATA-OUT

                      "Rod Harrison"
                      <rod.harrison@win        To:
<[email-masked]>
                      driver.com>              cc:

                      07/24/2002 10:24
                      PM

Folks,

             - Rod

---

From: "Rod Harrison" <[email-masked]>
Date: Wed, 24 Jul 2002 22:49:45 -0500

OK, it's been a long day. Let me try this one more time.

	I was write (almost) first time but I meant DATA-OUT instead of
DATA-IN. Here's what I meant to say ...

	There is a potential inconsistency in the description of the use of
the LUN field in DATA-OUT and R2T in the working v15 draft.

	9.7.3 Target Transfer Tag, for DATA-OUT last paragraph says ...

	"If the Target Transfer Tag is provided, then the LUN field MUST hold
a valid value and be consistent with whatever was specified with the
command;"

	"The Target Transfer Tag and LUN are copied in the outgoing data PDUs
and are used by the target only."

	Potentially a target could return a different LUN field in the R2T,
for perhaps some funky LUN mapping or other internal reason expecting
it to be copied to the DATA-OUT as per the R2T text.

	I think we need to indicate what is expected of the initiator if the
LUN field in the R2T does not match the LUN in the command PDU.

	- Rod

-----Original Message-----
From: Rod Harrison [mailto:[email-masked]]
Sent: Wednesday, July 24, 2002 8:57 PM
To: Julian Satran
Cc: [email-masked]
Subject: RE: iSCSI: v15 R2T and DATA-OUT

	- Rod

-----Original Message-----
From: Rod Harrison [mailto:[email-masked]]
Sent: Wednesday, July 24, 2002 8:51 PM
To: Julian Satran
Cc: [email-masked]
Subject: RE: iSCSI: v15 R2T and DATA-OUT

Julian,

	- Rod

-----Original Message-----
From: Julian Satran [mailto:[email-masked]]
Sent: Wednesday, July 24, 2002 5:00 PM
To: Rod Harrison
Cc: [email-masked]; [email-masked]
Subject: Re: iSCSI: v15 R2T and DATA-OUT

                      "Rod Harrison"
                      <rod.harrison@win        To:
<[email-masked]>
                      driver.com>              cc:

                      07/24/2002 10:24
                      PM

Folks,

             - Rod

---

From: Paul Koning <[email-masked]>
Date: Thu, 25 Jul 2002 10:35:00 -0400

> it to be copied to the DATA-OUT as per the R2T text.

I think that's a very bad idea and should not be permitted.

If someone wants to do LUN mapping, that's fine, so long as it's
transparent to the initiator.  To map a LUN and then let the mapped
number leak out to the initiator is broken.

> LUN field in the R2T does not match the LUN in the command PDU.

Given that the subject was brought up I tend to agree that the spec
should say something.  I would prefer it to say that this is a
protocol error.

	 paul