Subject: iSCSI: v15 R2T and DATA-OUT

From: "Rod Harrison" <[email-masked]>
Date: Wed, 24 Jul 2002 14:24:58 -0500

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: "Julian Satran" <[email-masked]>
Date: Thu, 25 Jul 2002 12:40:26 +0300

Rod,

I will fix the wording  - but you mentioned also TTT as part of Data-In - 
I was just commenting that there is no such thing.
As for the issue - if you check it when receiving R2T then you don't have 
to check it every time you copy it.
The word copy is just fine - I just have to make sure that checking on R2T 
is mandated.

Julo

"Rod Harrison" <[email-masked]>
07/25/2002 04:51 AM

        To:     Julian Satran/Haifa/IBM@IBMIL
        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

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
                      [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: Sanjay Goyal <[email-masked]>
Date: Thu, 25 Jul 2002 09:22:33 -0400

Hi
 if I read  draft-ietf-ips-iscsi-15-working.pdf
 from Julian's site
 
on page 159, 
 Data-In does have TTT field for the posAck case, when A bit is set to 1.
 
Regards 
Sanjay Goyal 

-----Original Message-----
From: Julian Satran [mailto:[email-masked]]
Sent: Thursday, July 25, 2002 5:40 AM
To: Rod Harrison
Cc: [email-masked]
Subject: RE: iSCSI: v15 R2T and DATA-OUT

Rod, 

I will fix the wording  - but you mentioned also TTT as part of Data-In - I
was just commenting that there is no such thing. 
As for the issue - if you check it when receiving R2T then you don't have to
check it every time you copy it. 
The word copy is just fine - I just have to make sure that checking on R2T
is mandated. 

Julo 

07/25/2002 04:51 AM 

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.

                - 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: "Julian Satran" <[email-masked]>
Date: Fri, 26 Jul 2002 12:03:56 +0300

I will add a strong statement about field consistency somewhere in 2.

Julo

                      "Rod Harrison"                                                                                                        
                      <rod.harrison@win        To:       Julian Satran/Haifa/IBM@IBMIL                                                      
                      driver.com>              cc:       <[email-masked]>                                                                  
                                               Subject:  RE: iSCSI: v15 R2T and DATA-OUT                                                    
                      07/26/2002 03:08                                                                                                      
                      AM                                                                                                                    

Julian,

             OK, that's the answer to my question then. The wording that's
there
right now doesn't say what the initiator should do if the LUN in an
R2T doesn't match the LUN it sent in the command PDU.

             So the resolution is that the initiator should treat a LUN
inconsistency between R2T and command as a protocol error. I suggest
we add a note to that effect where we talk about LUN in the R2T PDU
description, that would be 9.8.5 in the v15 working draft.

             - Rod

-----Original Message-----
From: Julian Satran [mailto:[email-masked]]
Sent: Thursday, July 25, 2002 6:53 PM
To: Rod Harrison
Cc: [email-masked]
Subject: RE: iSCSI: v15 R2T and DATA-OUT

Rod,

Probably a very long day. LUN is present in the command. Command is
associated with ITT. R2T can be checked for a consistent ITT and LUN.
End-story.

Julo

07/25/2002 06:49 AM

        To:        <[email-masked]>
        cc:        Julian Satran/Haifa/IBM@IBMIL
        Subject:        RE: iSCSI: v15 R2T and DATA-OUT

                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 ...

field MUST hold

outgoing data PDUs

                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

                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:

                     07/24/2002 10:24
                     PM

Folks,

            - Rod

---

From: "Julian Satran" <[email-masked]>
Date: Fri, 26 Jul 2002 11:52:01 +0300

Paul,

It would also be a bad idea to add too many words to the protocol.
The protocol is clear about field consistency.

Julo

                      Paul Koning                                                                                                           
                      <[email-masked]>          To:       [email-masked]                                                         
                      Sent by:                 cc:       [email-masked]                                                                    
                      [email-masked]        Subject:  RE: iSCSI: v15 R2T and DATA-OUT                                                    
                      .edu                                                                                                                  

                      07/25/2002 05:35                                                                                                      
                      PM                                                                                                                    

Excerpt of message (sent 24 July 2002) by Rod Harrison:
>
>            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
>            9.7.3 Target Transfer Tag, for DATA-OUT last paragraph says
...
> 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.

>            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.

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