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Dees, Brian M wrote:
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Thanks again for the information... but...
a) why not in original SATA or ATA/ATAPI-7
Specifically for Serial ATA, the SATA Revision 2.5 specification is a
single integration of Serial ATA 1.0a in addition to much of the Serial
ATA II material, including errata and design guides. The ICRC update
was simply applied to SATA Revision 2.5 with the understanding that this
new specification would replace the older set of documentation, which
leads to little need to update the old documentation when it is getting
replaced.
This new use of ICRC is a sigificant change in SATA error reporting. If
it is needed now (in SATA 2.5) why was it not needed in prior versions
of the SATA spec (or in ATA/ATAPI-7)? What is the justification for
adding it now if it was apparently not needed before?
b) the risk of using SATA that does not have this feature,
c) how are SATA CRC errors report by original SATA devices that did not
implement this feature?
The change was specific to allowing ICRC usage for reporting interface
CRC errors with Multi-word DMA and PIO protocols, previously it was only
allowed with the Ultra DMA protocol. Since this behavior was not
allowed prior to the change for either PATA or SATA, the impact of
reporting interface CRC errors with these other protocols should not be
specific to the transport.
I'm still trying to understand how the reporting of SATA CRC errors was
done prior to this change in the use of ICRC. If the original methods of
reporting SATA CRC errors was adequate then why this change to ICRC now?
And I really want to know what risk there is when using original SATA
that does not include this new use of ICRC to report SATA CRC errors.
It would really be nice if SATAIO would publish the original proposal
that caused this change to the SATA 2.x spec and also publish the
meeting minutes where this change was discussed and approved so that
everyone can why this change was needed and what problem(s) it is
solving and perhaps give some insight into the risks to data integrity
that exist prior to implementation of this change.
Are there millions of SATA devices in use that do not implement this use
of ICRC to report SATA interface CRC errors - do those devices represent
a risk (no matter how small) to the data stored and accessed on those
devices?
As I've said before, many people have seen data corruption problems with
SATA that could be directly related to a failure of the device or host
to detect and report SATA CRC errors to the host software. This change
to ICRC would appear to be an attempt to fix such problems in future
SATA implementions, is that what it is?
Hale
--
++ Hale Landis ++ [EMAIL PROTECTED] ++
