Re: iSCSI: iSCSI untagged task and SAM-2 SIMPLE task?

["John Hufferd" <hufferd@us.ibm.com>]

I am sorry that I failed to answer your first question, believe it or not,
I thought I had addressed it, Oh well...

What I was intending to say, along with the other stuff, was that since
your point was valid that the Untagged task was treated implicitly by the
Target as a Simple Task, the only key thing needed was to identify
approprate tasks as untagged tasks.  Everything else happened automatically
by the SCSI target layer.  The only thing iSCSI must do is identify to the
SCSI target layer that the Task is an Untagged Task, hence why we carry
that attribute, even when we carry an ITT for use by iSCSI.

The SAM2 document, 5.1 (the Execute Command Remote Procedure) says the
following about the Task Attribute: "... This argument shall not be
specified for an untagged command ..."  Therefore, the attribute field is
mutually exclusive with the untaggedness (I made up that word) of the task.
Hence, iSCSI uses its Attribute field (Attr) as follows:  if set to a non
zero value then it is a tagged task, but if zero, it signifies untagged.
It is the target SCSI layer that applies the attributes, and it will
implicitly apply the "Simple" attribute to any untagged task, in fact based
on the above, an untagged task is not supposed to be identified explicitly
as Simple or any other way.

I am not sure whether I answered your questions to your satisfaction, or
not.  But in case you want to really drill into me, please feel free to
also contact me off the reflector.
.
.
.
John L. Hufferd
Senior Technical Staff Member (STSM)
IBM/SSG San Jose Ca
Main Office (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
Home Office (408) 997-6136, Cell: (408) 499-9702
Internet address: hufferd@us.ibm.com


Luben Tuikov <luben@splentec.com>@ece.cmu.edu on 06/21/2002 06:28:50 PM

Please respond to iSCSI <ips@ece.cmu.edu>; Please respond to Luben Tuikov
       <luben@splentec.com>

Sent by:    owner-ips@ece.cmu.edu


To:    John Hufferd/San Jose/IBM@IBMUS
cc:    iSCSI <ips@ece.cmu.edu>
Subject:    Re: iSCSI: iSCSI untagged task and SAM-2 SIMPLE task?



Ok, the second question answered, but what about the first?

SAM-2 stipulates that an ``untagged'' task is a SIMPLE
task (SAM-2, 4.9.1 and 7.5.1). So, what is the purpose of the
iSCSI ``Untagged'' task? Shouldn't an ``untagged'' task
have iSCSI SIMPLE attribute (since iSCSI also has SIMPLE task
attribute just as per SAM-2)?

--
Luben