Re: single bit errors on files stored on USB-HDDs via USB2/usb_storage

[Matthias Schniedermeyer <ms@citd.de>]

Robert Hancock wrote:
> Matthias Schniedermeyer wrote:
>> Hi
>>
>>
>> I'm using a Bunch auf HDDs in USB-Enclosures for storing files.
>> (currently 38 HDD, with a total capacity of 9,5 TB of which 8,5 TB is
>> used)
> 
> All the same enclosure type?

36x"Fantec (was MaPower) DB-335U2-1" with Genesys-Logic-Chipset (at
least the model i used yesterday said that. I bought this 36 enclosures
in the time from May/2005 - October/2006, so it is possible that they
use different chipsets and/or revisions of the chipset)
2x"IOmega 33644" bought last week, with a Chipset that says it is from
IOMega, but i guess it is just a rebranded.
I have errors with all of them.

I have a spare enclosure Fantec DB-35U2-2, AFAICT it uses a
Cypress-Chipset which i haven't used for some time, so ATM i don't
remember if i had it with this one too.


>> This time i kept the defective files and used "vbindiff" to show me the
>> difference. Strangly in EVERY case the difference is a single bit in a
>> sequence of "0xff"-Bytes inside a block of varing bit-values that
>> changed a "0xff" into a "0xf7".
>> Also interesting is that each error is at a 0xXXXXXXX5-Position
>>
>> Attached is a file with 5 of the 6 differences named 1-5. Of each of the
>> 5 2x3 lines-blocks the first 3 lines are the original the following 3
>> lines contain the error in the middle row 6th value.
>>
>> NEVER did i see any messages in syslog regarding erros or an aborting
>> program due to errors passed down from the kernel or something like that.
> 
> The fact that the corruption seems data dependent would seem to me to
> point to some kind of hardware problem. I would tend to suspect the
> USB-to-IDE converters in the enclosures as being faulty or something
> like that..
> 


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