Re: Data in SCSI Response or SCSI Data

["Matt Wakeley" <matt_wakeley@agilent.com>]

Ok, maybe I'm missing something, but as I read the latest (July 10) draft, I see
this data/status thing working as follows.  I'm going to use psuedo code, so
that (perhaps) everyone might understand...

(Note that this whole discussion is only applicable to a target read operation)

/* as a target... */
if ((this is the last iSCSI data PDU to send to fullfill the SCSI command) and
    (this SCSI STATUS is GOOD (except for residual counts)) then
{
  set the "S" bit in the iSCSI DATA PDU header
  /* setting the "S" bit explicitely defines "end of exchange" */
  update the "iSCSI Status" field in the iSCSI DATA PDU header
  if (there is a residual count) then
  {
    set the "O" or "U" bits and update the
    "Residual Count" field of the iSCSI DATA PDU header
  }
  send the last iSCSI DATA PDU (completing the SCSI command)
}
else
{
  clear the "S" bit in the iSCSI DATA PDU header
  send the iSCSI DATA PDU
  if (the last iSCSI DATA PDU was sent)
  {
    create the iSCSI RESPONSE PDU
    send it
  }
}

Now, what exactly is the big issue that's required all this discussion?

-Matt Wakeley
Agilent Technologies


Douglas Otis wrote:

> Julo,
>
> After painfully understanding your status here not there conversation and
> being ensured Autosense is now a fact of life, rather than placing status
> within a READ PDU, perhaps you should consider simply revising the
> definition of the flags and use a common DATA PDU.  Change the Status bit to
> indicate Error Detected and perhaps add a bit to signal End of Exchange.
> From End of Exchange you could deduce Good Status.  I see little benefit in
> status presented twice or dummy status sent with partial exchanges.  It only
> seems to make room for conflicts.  (The two values not agreeing, I, on the
> other hand, will never agree.)  At what point would the O, and U flags be
> valid?  Would this be a result of an error?  If so, perhap these flags could
> be left to response PDU.
>
> Doug