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RE: iSCSI: changing MaxPDUDataLength
Julian,
Another problem here is that the
target has to calculate the offset from the DataSN #. And as BegRun can be
any value. E.g., BegRun=4 and RunLngth=0 means starting DataSN=4, send all
the data for that sequence.
I think it would be a performance hit and waist of
memory to keep a tally of all PDU sizes just for an occasional
SNACK.
It's not that it can't be done ... it is more that it
is messy and I think there is a solution that will satisfy the design
requirements but keep the software simpler.
Eddy
That is not completely accurate. The only problem is when PDU size decreases and then SNACK must be for
all data. Target can also keep a
mapping of numbers/to offsets (the list should be small and if it gets long
ask for ack (A-bit).
Julo
| Eddy Quicksall
<eddy_quicksall@ivivity.com> Sent by: owner-ips@ece.cmu.edu
06/08/2002 10:54 PM Please respond to Eddy Quicksall
| To:
pat_thaler@agilent.com cc:
ips@ece.cmu.edu
Subject: RE: iSCSI:
changing MaxPDUDataLength
|
Thanks,
As a target, I won't be able to let
it change until all of the outstanding commands are finished (running with
ErrorRecoveryLevel>=1). This is because I must use the PDU size to
compute the offset from a SNACK's BegRun/RunLength.
So, I plan to
not give the text response for a MaxPDURecvDataLength in FFP until I get
back an ExpStatSN == next StatSN.
This will cause a delay of unknown
time before the PDU size can actually change ... do you see any problem
with this?
Eddy
-----Original Message----- From:
pat_thaler@agilent.com [mailto:pat_thaler@agilent.com] Sent: Friday, June
07, 2002 1:13 PM To: eddy_quicksall@ivivity.com;
ips@ece.cmu.edu Subject: RE: iSCSI: changing
MaxPDUDataLength
Eddy,
If one uses a message sync and
steering that relys on the transport segments carrying a full PDU, e.g. TCP
ULP Framing Protocol (TUF), then if the path MTU changes one would want to
change the PDU data length to fit the new
path MTU.
Pat
-----Original Message----- From: Eddy
Quicksall [mailto:eddy_quicksall@ivivity.com] Sent: Wednesday, June 05,
2002 12:24 PM To: ips@ece.cmu.edu Subject: iSCSI: changing
MaxPDUDataLength
Does anybody know a case where it is necessary to
support a new PDU data length during full feature
phase?
Eddy mailto:
Eddy_Quicksall@iVivity.com
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Last updated: Mon Jun 10 20:18:49 2002
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