Re: iSCSI: header digest error at initiator

[Matt Wakeley <matt_wakeley@agilent.com>]

Santosh Rao wrote:

> > Second, you say that initiators and targets routinely perform scoreboarding.
> > How is this done today?  Buffer(s) are provided to an I/O chip.  The I/O chip
> > writes the data into the buffers.  It does not have the memory to determine
> > that each and every byte has been written to. So how is the initiator/target
> > supposed to be absolutely sure that every byte was written to?
> 
> The initiator would use a check along the following lines  :
> 
> (total bytes xfer'ed as indicated by the chip ) =
> (no. of bytes of data xfer specified by ULP) - (resid reported by the target in
> SCSI Response PDU).
> 
> to verify that all the data the target sent is accounted for at the initiator
> end.

I think you need to use a different word than score boarding.

Score boarding means that you have a big "map" that describes every byte of
data you want to receive.  As each byte is received, you "check off" the
indicator for that byte that indicates that it was received.  When all the
indicators are checked off, you have all the data.  Score boarding is not a
mathematical calculation.

-Matt