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

[Pete Zaitcev <zaitcev@redhat.com>]

On Thu, 07 Dec 2006 20:41:12 +0100, Matthias Schniedermeyer <ms@citd.de> 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), and also
use decent cables.

-- Pete