Subject: Re: iSCSI: FirstBurstSize, etc

From: "Julian Satran" <[email-masked]>
Date: Fri, 12 Oct 2001 01:50:45 +0300

Eddy,

I am going to make some changes related to PDUsize. I will fix this 
discrepancy and publish the suggested 09 text soon.

Thanks,
Julo

"Eddy Quicksall" <[email-masked]>
11-10-01 22:22
Please respond to "Eddy Quicksall"

        To:     Julian Satran/Haifa/IBM@IBMIL, <[email-masked]>
        cc: 
        Subject:        iSCSI: FirstBurstSize, etc

I am wondering about the following statement:

  FirstBurstSize MUST NOT exceed MaximumBurstSize.

It doesn't seem to fit the various definitions. I made the following 
diagram
from the definitions and FirstBurstSize came out larger then MaxBurstSize.

Here are the definitions I am going by:

25 FirstBurstSize
 Initiator and target negotiate the maximum amount of unsolicited data
 an iSCSI initiator may send to the target, during the execution of a
 single SCSI command, in units of 512 bytes.

24 MaxBurstSize
 Initiator and target negotiate maximum SCSI data payload in an iSCSI
 sequence (a sequence of Data-In or Data-Out PDUs ending with a Data-In
 or Data-Out PDU with the F bit set to one) in units of 512 bytes.

I get the definition of a sequence from "2.2.2.3 Data Sequencing":

 For output data PDUs, DataSN starts with 0 for the first data PDU of a
 sequence (the initial unsolicited sequence or any data PDU sequence
 issued to satisfy an R2T) and advances by 1 for each subsequent data
 PDU.

         |<------------------ Unsolicited data ------------------->|
         |                    |<------------ Sequence ------------>|
|Command | Immediate Data  |  |<---- Remaining unsolicited ------->|
|========|=================|  |================|  |F===============|
         |<-DataPDULength->|  | DataPDULength  |  | DataPDULength  |
                              |<--------- MaxBurstSize ----------->|
         |<------------------- FirstBurstSize -------------------->|

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