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

[Douglas Gilbert <dgilbert@interlog.com>]

Alan Stern wrote:
> On Tue, 30 Sep 2008, Martin K. Petersen wrote:
> 
>>>>>>> "Alan" == Alan Stern <stern@rowland.harvard.edu> 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