Re: iSCSI : Section 2.4.2. Error Communication Latencies.

[Sandeep Joshi <sandeepj@research.bell-labs.com>]

your question has been asked once before.
see http://ips.pdl.cs.cmu.edu/mail/msg03453.html

scroll to where it says "Section 2.4.2".

-sandeep

Santosh Rao wrote:
> 
> All,
> 
> The rev 05 draft mandates targets to wait until all the Data PDUs of an
> exchange have been received, prior to communicating any error with the
> I/O that may have occurred on an earlier I/O. Why is this needed ? This
> only adds additional latency to error communication from target to
> initiator and can cause large delays in communicating an error with long
> lasting I/Os like tape.
> 
> The ability to communicate an error on its occurrence is something other
> SCSI transports provide and it requires the target to be capable of
> safeguarding against the arrival of stale frames of a PDU from an old
> exchange, something which should be possible and required in any case.
> 
> Regards,
> Santosh
> 
>  Section 2.4.2, pg 36
> ---------------
> "If a SCSI device error is detected while data from the initiator is
> still expected (the command PDU did not contain all the data and the
> target has not received a Data PDU with the final bit Set) the target
> MUST wait until it receives the a Data PDU with the F bit set before
> sending the Response PDU."