Re: iSCSI: header digest error at initiator

[Matt Wakeley <matt_wakeley@agilent.com>]

Santosh Rao wrote:
> 
> If this is the intention of the recommended error recovery, it is the
> result of not allowing score-boarding. By score-boarding an initiator
> would detect an underrun and would just error the affected I/O back.

Two comments here.  First, in your example, the initiator is inventing an
error that really didn't occur in the target.  The target completed the I/O
successfully, it was the transport that experienced an error, but you're
treating it like a target error.

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?

> this case, all outstanding tasks on that connection are being affected.
> 
> Both the Format Error and Digest Error handling seem too extreme. A
> format error or digest error recovery should only involve the affected
> task and none others.
> 
> Thanks,
> Santosh

-Matt Wakeley