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

[Matthias Schniedermeyer]

Pete Zaitcev wrote:
> On Thu, 07 Dec 2006 20:41:12 +0100, Matthias Schniedermeyer <ms@xxxxxxx> wrote:
> 
> 
>>>>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)
>>>>[....]
>>>>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".
> 
> 
>>>This was almost certainly caused by hardware flaws in the USB interface 
>>>chips of the enclosures.  There's nothing the kernel can do about it 
>>>because the errors aren't reported; all that happens is that incorrect 
>>>data is sent to or from the drive.
>>
>>So pretty much all ich can do is to pray that the errors don't corrupt
>>the Filesystem-Metadata (XFS).
> 
> 
> No, this is not all. You should buy a variety of different enclosures
> with different chipsets (e.g. find a Freecom if you can),

That would definetly cost way to much money and time to be in any way
"efficient".

> and also use decent cables.

I replaced all cables with "High Quality"-cables.
But as a "Joe user" it is practically impossible to really know if the
cables are good.
All i can say is that the "original" cables that came with the
enclosures appear a bit thin and the ones i bought appear much more
thick, have gold plated contacts and have a massive plaited shielding
IOW appear much more trustworthy. But, as i said, in the end i can't
really know if they are better than the original ones.




Bis denn

-- 
Real Programmers consider "what you see is what you get" to be just as
bad a concept in Text Editors as it is in women. No, the Real Programmer
wants a "you asked for it, you got it" text editor -- complicated,
cryptic, powerful, unforgiving, dangerous.

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