Re: iSCSI: CmdSN past R + 2**31 - 1

["Mallikarjun C." <cbm@rose.hp.com>]

Monisha,

If you're looking for reasons behind this rule, I recommend going through the
ips archives during October/November 2001 timeframe - search for the keyword "X bit".

But reading the text on page 32, I can see that it's somewhat cryptic, and
had a typo (the cross-reference should be only to section 8.3 of rev11, or
8.4 of rev11.90 - not also to 9.3), and does not capitalize the "not" in "MUST not".
I suggest the following text for consideration as the replacement to the quoted
text:

"If an initiator issues a command retry for a command with CmdSN R on a
connection when the session CmdSN register is Q, it MUST NOT advance
the CmdSN past R + 2**31 -1 unless a different non-immediate command
with CmdSN equal or greater than Q was issued on the same connection
if the connection is still operational, and the reception of the command is
acknowledged by the target (see section 8.4 Command Retry and Cleaning
Old Command Instances).  The second non-immediate command when sent,
MUST be sent in-order after the retried command on the same connection."

Finally, I also see that section 8.4 differs from the above in applicability.  It seems
to me that "from the CmdSN of the retried command" should replace
"since the retry was issued" in the following .  [ Julian, please correct if I'm missing
something here. In any case, there seems to be a consistency issue. ]

"a non-immediate command be issued and acknowledged within a 2**31-1
commands interval since the retry was issued.

Thanks.
--
Mallikarjun

Mallikarjun Chadalapaka
Networked Storage Architecture
Network Storage Solutions Organization
Hewlett-Packard MS 5668
Roseville CA 95747
cbm@rose.hp.com

----- Original Message -----
From: "Monisha Barooah" <monishabarooah@myrealbox.com>
To: <cbm@rose.hp.com>
Sent: Sunday, March 31, 2002 6:03 AM
Subject: CmdSN past R + 2**31 - 1



Hi Mallikarjun,
 The following is an extract from Page 32 of the iSCSI draft 11

When the current value of the CmdSN register is Q, an initiator MUST not advance CmdSN past R + 2**31 - 1
after reissuing a command with CmdSN R on a connection while this connection is operational, unless a new non-
immediate command with CmdSN equal or greater than Q was issued on the given connection and its reception
acknowledged by the target (see Section 9.3 Command Retry and Cleaning Old Command Instances Section 8.3
Command Retry and Cleaning Old Command Instances). The non-immediate command MUST be sent in order after the
retried command.

What does this mean? Can I get an explaination of this.

Regards,
Monisha.