RE: iSCSI: v15 R2T and DATA-OUT

[Eddy Quicksall <eddy_quicksall@ivivity.com>]

There should not be a requirement for the initiator to check for
consistency. This would just serve to impact performance. It would be OK to
check but the target should be responsible to set the LUN correctly and the
initiator should just copy it as is.

BTW, the LUN in the R2T only has use by the target ("are used by the target
only"). If the target doesn't need it, then why should it take the time to
supply it?

Does anyone know why this is in the R2T anyway? It would seem like the TTT
would say it all.

Eddy

-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Friday, July 26, 2002 5:04 AM
To: ips@ece.cmu.edu
Subject: RE: iSCSI: v15 R2T and DATA-OUT


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:       <ips@ece.cmu.edu>

                                               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:Julian_Satran@il.ibm.com]
Sent: Thursday, July 25, 2002 6:53 PM
To: Rod Harrison
Cc: ips@ece.cmu.edu
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


"Rod Harrison" <rod.harrison@windriver.com>
07/25/2002 06:49 AM

        To:        <ips@ece.cmu.edu>
        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 ...

                "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 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:rod.harrison@windriver.com]
Sent: Wednesday, July 24, 2002 8:57 PM
To: Julian Satran
Cc: ips@ece.cmu.edu
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:rod.harrison@windriver.com]
Sent: Wednesday, July 24, 2002 8:51 PM
To: Julian Satran
Cc: ips@ece.cmu.edu
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:Julian_Satran@il.ibm.com]
Sent: Wednesday, July 24, 2002 5:00 PM
To: Rod Harrison
Cc: ips@ece.cmu.edu; owner-ips@ece.cmu.edu
Subject: Re: iSCSI: v15 R2T and DATA-OUT


There is no TTT for data-In. Julo



                     "Rod Harrison"
                     <rod.harrison@win        To:
<ips@ece.cmu.edu>
                     driver.com>              cc:
                     Sent by:                 Subject:  iSCSI: v15
R2T and DATA-OUT
                      owner-ips@ece.cmu
                     .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