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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: iSCSI - positive data ack - change proposalI don't believe this proposal adequately protects the target from resource limitations. This works fine for 1 long running read command, but what about a full command window of read commands each taking 50 or even just 10 DATA-IN PDUs? Seems to me that the target will have to be so conservative that it will end up setting the F bit on almost every DATA-IN, or at least every few. If we end up with that many data ACKs we might as well go along with Santosh's proposal of in-band ACKing. Although I have to admit I don't see how missing DATA-IN PDUs can be detected with in-band ACKs since the next DataSN on a given command can't be predicted. I suppose we could add a previousDataSN to the DATA-IN PDU. I would prefer to see data ACKs dropped. - Rod -----Original Message----- From: owner-ips@ece.cmu.edu [mailto:owner-ips@ece.cmu.edu]On Behalf Of BURBRIDGE,MATTHEW (HP-UnitedKingdom,ex2) Sent: Monday, September 24, 2001 11:39 AM To: 'Julian Satran'; ips@ece.cmu.edu Subject: RE: iSCSI - positive data ack - change proposal Julian This looks good! A couple of comments: Please could you add a paragraph to state that a target does not necessarily need to wait for the acknowledgment of a sequence before starting transmission of the next sequence - for performance reasons. In section 3.7.1 it states that "Upon receiving an Data-In PDU with the F set to 1 in a session with ErrorRecoveryLevel 1 or higher the initiator MUST issue a DataACK type of SNACK indicating the next expected DataSN for this task". Is this true for all incoming data sequences including the final sequence of the transfer? Cheers Matthew -----Original Message----- From: Julian Satran [mailto:Julian_Satran@il.ibm.com] Sent: Sunday, September 23, 2001 2:46 AM To: ips@ece.cmu.edu Subject: Re: iSCSI - positive data ack - change proposal Here is updated version (in the previous I had excluded the sequences ended with Status with no good reason. Julo (See attached file: ack.txt) ----- Forwarded by Julian Satran/Haifa/IBM on 23-09-01 04:41 ----- Julian Satran To: ips@ece.cmu.edu 22-09-2001 cc: 14:04 From: Julian Satran/Haifa/IBM@IBMIL Subject: iSCSI - positive data ack - change proposal Dear colleagues, As I mentioned earlier all the elements needed for positive data-ack are already in place. I am suggesting the following changes to the document to reintroduce the data-ACK. Comments? Julo **** Attachment ack.txt has been removed from this note on 23 September 2001 by Julian Satran ****
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