RE: iSCSI: draft 7: Final bit in Data PDUs

["Julian Satran" <Julian_Satran@il.ibm.com>]

Elliot,

Thanks .  Will change 2.7.1 to read:

1.1.1     F (Final) Bit

   For outgoing data, this bit is 1 for the last PDU of unsolicited data or
   the last PDU of a sequence answering a R2T.

   For incoming data, this bit is 1 for the last input (read) data PDU of a
   sequence.  Input can be split in several sequences each one having it's
   own F bit. Splitting in sequences does not affect DataSN counting on
   Data-IN PDUs but MAY be used as a "change direction" indication for
   Bidirectional operations that need such a change and/or end of
   recoverable sequences by targets with a limited replay buffer.

   For Bidirectional operations, the F bit is 1 both for the end of the
   input sequences as well as the end of the output sequences.

 Comments?

 Julo

"Elliott, Robert" <Robert.Elliott@compaq.com>@ece.cmu.edu on 07-08-2001
20:25:13

Please respond to "Elliott, Robert" <Robert.Elliott@compaq.com>

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


To:   ips@ece.cmu.edu
cc:
Subject:  RE: iSCSI: draft 7: Final bit in Data PDUs



I think an F bit per direction would be most useful.

Bidirectional command background:  the target chooses what order to run the
reads and writes.  It can start with either, and switch from one to the
other as often as it wishes.  These are all legal:

1.  read all data, write all data
2.  write all data, read all data
3.  read some, write some, read some, ...
4.  write some, read some, ...

There are two independent data pointers active, one per stream.  EMDP
applies to both.

--
Robert.Elliott@compaq.com
Compaq Computer Server Storage


-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Monday, August 06, 2001 5:57 PM
To: ips@ece.cmu.edu
Subject: Re: iSCSI: draft 7: Final bit in Data PDUs


Elliot,

I have no clue how those commands are going to work.
Can you help?
I assume that the F bit will have to be there at both ends?

Julo

"Elliott, Robert" <Robert.Elliott@compaq.com>@ece.cmu.edu on 06-08-2001
18:02:10

Please respond to "Elliott, Robert" <Robert.Elliott@compaq.com>

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


To:   "'ips@ece.cmu.edu'" <ips@ece.cmu.edu>
cc:
Subject:  iSCSI: draft 7: Final bit in Data PDUs



iSCSI draft 7 section 2.7.1 describes when the (F) Final bit is
set in the Data-out and Data-in PDUs:

  For outgoing data, this bit is 1 for the last PDU of unsolicited
  data  or the last PDU of a sequence answering a R2T.

  For incoming data, this bit is 1 for the last input (read) data
  PDU of a sequence.

It needs to define how this works for bidirectional commands.
Is the F bit set to one on both the last Data-out PDU and the last
Data-in PDU?  Or is it set to one only on the last Data PDU,
whatever direction it may be?

--
Robert.Elliott@compaq.com
Compaq Computer Server Storage