SBP 1394 hard drives hang with Windows XP (rare)

JimMcGrath at oaktech.com JimMcGrath at oaktech.com
Mon May 12 11:46:28 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* JimMcGrath at oaktech.com
*





Pat's correct.  ATA has this limit, ATAPI+MMC set (used in optical dries)
does not have this limit.  It is more likely that some other piece of
software has a limit.  As Pat point out, if the testing was not through
enough (perhaps because the tester "knew" ATA had the 128 KiB limit), then
you could see the same problem with optical drives due to a common fault in
the higher level software.

Jim McGrath
Oak Technology
Sr Director of Strategy and Product Planning
Office of the CTO
1390 Kifer Road
Sunnyvale, CA 94086
Ph: (408) 523-6683
Em: jimmcgrath at oaktech.com
Wb: http://www.oaktech.com




                                                                                                                                       
                      "Pat LaVarre"                                                                                                    
                      <LAVARRE at iomega.c        To:       "SBP-3" <SBP3 at ISG.Apple.com>                                                  
                      om>                      cc:       "NCITS T10" <T10 at t10.org>                                                     
                      Sent by:                 Subject:  RE: SBP 1394 hard drives hang with Windows XP (rare)                          
                      owner-t10 at t10.org                                                                                                
                                                                                                                                       
                                                                                                                                       
                      05/12/2003 09:14                                                                                                 
                      AM                                                                                                               
                                                                                                                                       
                                                                                                                                       




* From the T10 Reflector (t10 at t10.org), posted by:
* "Pat LaVarre" <LAVARRE at iomega.com>
*
> Discussions in Nashua ...

Thanks for sharing.

> > > the conclusion that the problem is likely
> > > caused by a bridge chip failure
> > > to split > 128 KiB RBC operations
> > > into more than one ATA command for the attached
> > > device. ATA can't transfer more than 128 KiB in
> > > a single command.
> >
> > I would also guess that this problem is not only
> > limited to hard drives, but perhaps to optical
> > drives and other ATA/ATAPI device types as well.
>
> I would agree.

Why?

This ATA limit is decided by opcode.  Same for SCSI.

SCSI invented new opcodes to raise its 21 bit LBA
limit to 32, and its 8 bit block TransferLength limit
to 16.

ATA invented new opcodes to raise its 28 bit LBA limit
to 48, and its 8 bit block TransferLength limit to 16.

To find a compliant ATAPI device that chokes over more
than 128 / 0.5 blocks per op, we have to find one that
chokes over more than 21 bits per LBA.

That's hard to do now, especially in the optical
space.

No?

Are we just saying it's easy to find a bridge that
copies only one byte of TransferLength to IDE from
ORB, rather than two, no matter the op?

Help?  I'm lost.

> ATA can't transfer more than
> 128 KiB in a single command.

That is, not with any of its 28-bit LBA ops.

Also Microsoft's penchant for choking off data per CDB
down below 1 MiB means Windows doesn't much test lots
of blocks per ATA command.

Also I wonder about across how many bytes the IDE UDma
CRC stretches comfortably.  I think I remember T13
folk had an answer, last time I asked.

Pat LaVarre

             -----Original Message-----
             From: Peter Johansson [mailto:PJohansson at ACM.org]
             Sent: Fri 5/9/2003 8:18 AM
             To: SBP-3
             Cc: NCITS T10
             Subject: RE: SBP 1394 hard drives hang with Windows XP (rare)



             At 01:18 PM 5/5/2003 -0700, Mike Berhan wrote:

             >The program worked on both computers; both drives could read
up to the
             >full 512K in a single I/O.
             >
             >I then modified the app to write back the data from the
previously read
             >location.  Both drives hung the same way when the sector
count reached
             >257. That matches with your 128K per ORB limitation.

             Discussions in Nashua led to the conclusion that the problem
is likely
             caused by a bridge chip failure to split > 128 KiB RBC
operations into more
             than one ATA command for the attached device. ATA can't
transfer more than
             128 KiB in a single command.

             >It appears to only be on writes though, at least from what
I've seen so far.

             It's difficult to understand why a bridge chip should be
handling reads
             correctly but tripping up on writes ...

             >Perhaps that piece of core logic is used in bridge chips by
multiple vendors?

             Based on anecdotal experience, I think this is unlikely.

             >I would also guess that this problem is not only limited to
hard drives,
             >but perhaps to optical drives and other ATA/ATAPI device
types as well.

             I would agree.


             Regards,

             Peter Johansson

             Congruent Software, Inc.
             98 Colorado Avenue
             Berkeley, CA  94707

             (510) 527-3926
             (510) 527-3856 FAX

             PJohansson at ACM.org


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