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From: Oliver Neukum <oliver@neukum.org>
To: Ben Nizette <ben.nizette@iinet.net.au>
Subject: Re: single bit errors on files stored on USB-HDDs via USB2/usb_storage
Date: Sat, 9 Dec 2006 09:18:26 +0100
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Cc: Matthias Schniedermeyer <ms@citd.de>,
       Stefan Richter <stefanr@s5r6.in-berlin.de>,
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Am Samstag, 9. Dezember 2006 07:11 schrieb Ben Nizette:
> >>> Also, you mentioned that the corruption occurs systematically on certain
> >>> byte patterns. Therefore it's certainly not related to the cables.
> >> It'd guess that too, but who can that say for sure. :-|
> > 
> > You may have a bit pattern that stresses the controllers and suddenly
> > a marginal cable may matter.
> 
> The errors occur in strings of 0xFFs.  From the USB standard:
> 
> a “1” is represented by no change in level and a “0” is represented by a 
> change in level

Yes, plus added stuffing bits.

> so this error-infested bytes are effectively long, quiet times on the 
> wire.  I would have thought this would be the _least_ stressful time for 
> the controllers but maybe they are also more susceptible to noise during 
> this period.

The longer you don't change the voltage the likelier are reciever and
transmitter to get out of sync.

	Regards
		Oliver