Re: [PATCH 1/3] SCSI: rearrange code in scsi_io_completion

[Douglas Gilbert <dgilbert@xxxxxxxxxxxx>]

Alan Stern wrote:
> On Tue, 30 Sep 2008, Martin K. Petersen wrote:
>
> > > > > > > "Alan" == Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes:
> > Alan> Are there types of failure for which we really don't want to
> > Alan> print anything?  For example, what about UNIT ATTENTION for
> > Alan> media changes or the DIX/DIF failures (should those both be
> > Alan> DIF?)?
> >
> > ILLEGAL REQUEST + 10/[123] indicates that the HBA rejected the request
> > (DIX).
> >
> > ABORTED COMMAND + 10/[123] indicates that the device found a
> > corruption error (DIF).
>
> That answer the parenthetical question.  Do you know the answer to the 
> main question?  That is, when either of these events occurs do we want 
> to skip adding an error message to the system log?

I know that SAS maps certain types of transport errors to
"ABORTED COMMAND" (see
http://www.t10.org/ftp/t10/drafts/sas2/sas2r14e.pdf
section 10.2.3) and they should be retried, especially the
timeouts.

For example, if there are 20 disks hanging off a SAS expander
with a 4 wide link back to the host, then issuing big and
very frequent READs to those 20 disks should see some
"ABORTED COMMAND"s.

Doug Gilbert

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