Re: how much "Desired Data Transfer Length" in R2T

["Subrahmanya Sastry K.V" <skotra@npd.hcltech.com>]

inline

Nitin Dhingra wrote:

> Hi sastry,
> What you specified is during negotiation, I am referring to after the
> negotiation, when
> DataPDULength has been decided. But Later when R2T's needs to be send from
> target,
> examples have been given in the draft that depicts one R2T is sent from the
> target and it receives
> 2 Data PDU's. It means that target specified more size than DataPDULength
> in the R2T,


As per section 3.8 of iscsi-draft-08:

"The data length of the Data PDU MUST
  not exceed the Desired Data Transfer Length specified in the R2T. "

This means that the target may mention a greater value for Desired Data
Transfer Length
than the initiator can send at a time i.e.,  the DataPDULength of the
initiator.
In that case the data lengths of one or more Data PDUs (from the initiator)
add up to  the value of Desired Data Transfer Length. This is indicated by the
F bit
of the last Data PDU set to 1.


Suppose the initiator has the DataPDULength of 5k.

The target asked for 10k (Desired Data Tranfer Length) and sent an R2T.

Now the initiator sends two DataPDUs of data length 5k each to fulfill the
request.



> on what
> basis did the target decide that.
>
> Thanks,
> nitin

This is what I understood. comments ?

Sastry