Messages in this thread | | | Date | Thu, 07 Dec 2006 23:57:07 +0100 | From | Matthias Schniedermeyer <> | Subject | Re: single bit errors on files stored on USB-HDDs via USB2/usb_storage |
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DervishD wrote: > Hi Matthias :) > > * Matthias Schniedermeyer <ms@citd.de> dixit: > >>My averate file size is about 1GB with files from about 400MB to >>5000MB I estimate the average error-rate at about one damaged file in >>about 10GB of data. >> >>I'm not sure and haven't checked if the files are wrongly written or >>"only" wrongly read back as i delete the defective files and copy them >>again. >> >>Today i copied a few files back and checked them against the stored MD5 >>sums and 5 files of 86 (each about 700 MB) had errors. So i copied the 5 >>files again. 4 of the files were OK after that and coping the last file >>the third time also resulted in the correct MD5. > > > I had more or less the same issue a week or two ago. I performed > lots of tests and only by replacing the USB2.0 PCI card, the USB cable > and the power supply of the usb-hdd adapter got the problem solved. > > I'm not sure if the problem is really gone, but the system works now > reliably. I don't know if sooner or later I'll get the issue again, > because I didn't really identify a culprit: looks like the > card+adapter+cable combination was just "ugly", and errors from the > adapter were not reported correctly.
The 38 HDDs are in 38 enclosures, so each has it's own power supply. I have used different cables and i replaced the USB-Controller once.
So it can't be a single faulty component. Except when the computer itself would be the culprit.
>>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 same here! Looks like USB-HDD adapters don't report any errors > to the kernel :????? > > The best advice I can give you, from my limited experience with the > problem, is: replace the cable. This minimizes the chance of corrupted > data getting into the adapter. If that doesn't solve the problem, try > removing any unconnected cable that is plugged into the USB card. > Believe it or not, a long but unconnected cable (put there just to be > able to plug my USB card-reader without having to look for the cable in > a drawer) was causing errors *even in a Kingston USB key that worked > flawlessly otherwise*!!!
Hmmm. That's the only thing that i currently may be doing wrong. I have a 1,5 Meter and a 4,5 Meter cable connected to the USB-Controller and i only use of them depending on where the HDD is placed in my room, the other one is dangling unconnected.
Then i will unconnect the short cable and use the long cable exclusivly and see if it gets better(tm).
> If you have any other question, feel free to drop me a note. I'm > sorry I cannot give a much more technical or scientific answer, but > unfortunately I have none :((
Thank you anyway.
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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