SBP 1394 hard drives hang with Windows XP (rare)

Mike Berhan mikeb at
Mon May 5 10:18:23 PDT 2003

* From the T10 Reflector (t10 at, posted by:
* "Mike Berhan" <mikeb at>
> IIRC, some older Symbios bridges had a 128K per ORB limitation. There's a
> workaround for this problem in the Linux SBP-2 driver.

Thanks for the information.  Here is some additional information.  I have
written a simple Windows test application that reads 128 sectors and
increments by one sector in a loop up to 1024 sectors.  I have two different
systems as follows:

Windows XP - SmartDisk FireLite 20GB 1394 drive - TI Lynx bridge chip?
Windows 2000 - Oxford Semiconductor FW911-TQ-A bridge chip

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.  It appears to only be on
writes though, at least from what I've seen so far.  Perhaps that piece of
core logic is used in bridge chips by multiple vendors?  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.

On the SmartDisk system, the drive was hung and stayed hung.  On the Oxford
Semi system, after the timeout, the drive was accessible again.

These are two recently purchased drives.  I wonder if the drive vendors know
about this problem.  The end result can be worse than just a hung I/O as I
have had this problem corrupt my hard drive.  Although >128K per I/O is rare
with Windows, it can happen.

I am making this simple test application available to any of the vendors
that want to use it for their testing.  You should ONLY run this on a test
drive as you should assume it will corrupt the drive.  If you're interested,
please e-mail me at mikeb at  Thank you.

Mike Berhan
busTRACE Technologies
807 Douglas Blvd., Suite 130
Roseville, CA  95678
Phone 916-782-6341
Fax 916-773-2056

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