Messages in this thread | | | Date | Wed, 06 Dec 2006 23:01:54 +0100 | From | Matthias Schniedermeyer <> | Subject | single bit errors on files stored on USB-HDDs via USB2/usb_storage |
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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)
After i realised about a year(!) ago that the files copied to the HDDs sometimes aren't identical to the "original"-files i changed my procedured so that each file is MD5 before and after and deleted/copied again if an error is detected.
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.
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.
Data for the computer/software: Hardware: Computer is a Dual P3-933Mhz with 3GB (ECC) SD-RAM, Severworks HE-SL-Chipset Source-HDD is a 200GB S-ATA device connected to a Promise TX-4 using libata. Destination-HDDs: Several different models in several different enclosures and different chipsets, mostly Genesys Logic) USB-controller: Currently i use a EHCI/OHCI-NEC-Chipset add-on card but since about 4-5 month ago i used a EHCI/UHCI-VIA-Chipset add-on card with same results. Software: Kernel: <What was current 1 year ago> up to 2.6.18, self compiled vanilla kernels. I haven't tried 2.6.19 and i don't expect any changes from it. Distribution: Debian SID
I you need any other information i will provide them as good as i can.
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.
1: 245A E2F0: 0E D9 35 01 00 F4 7B F8 00 00 01 E0 09 00 80 00 ..5...{. ........ 245A E300: 0D FF FF FF FF FF FF FF FF FF FF FF FF FF DF FC ........ ........ 245A E310: 20 92 50 90 DC F4 0C 1A 1A 18 DB 80 4E 61 25 80 .P..... ....Na%.
245A E2F0: 0E D9 35 01 00 F4 7B F8 00 00 01 E0 09 00 80 00 ..5...{. ........ 245A E300: 0D FF FF FF FF F7 FF FF FF FF FF FF FF FF DF FC ........ ........ 245A E310: 20 92 50 90 DC F4 0C 1A 1A 18 DB 80 4E 61 25 80 .P..... ....Na%.
2: 24F9 F770: 00 00 01 E0 09 00 80 00 0D FF FF FF FF FF FF FF ........ ........ 24F9 F780: FF FF FF FF FF FF FC 13 64 0B 38 68 EA A2 11 86 ........ d.8h.... 24F9 F790: 61 7A EE EC ED 1D 6F 31 32 6E 4D D9 B5 31 37 66 az....o1 2nM..17f
24F9 F770: 00 00 01 E0 09 00 80 00 0D FF FF FF FF FF FF FF ........ ........ 24F9 F780: FF FF FF FF FF F7 FC 13 64 0B 38 68 EA A2 11 86 ........ d.8h.... 24F9 F790: 61 7A EE EC ED 1D 6F 31 32 6E 4D D9 B5 31 37 66 az....o1 2nM..17f
3: 20CB C6B0: 00 FB 3F F8 00 00 01 E0 09 00 80 80 0D 21 2A 1B ..?..... .....!*. 20CB C6C0: 65 F1 FF FF FF FF FF FF FF FF 3E C4 BC 2B 39 A4 e....... ..>..+9. 20CB C6D0: 8E 85 50 EB 7B 02 7B 93 79 77 50 EF 60 32 8C 03 ..P.{.{. ywP.`2..
20CB C6B0: 00 FB 3F F8 00 00 01 E0 09 00 80 80 0D 21 2A 1B ..?..... .....!*. 20CB C6C0: 65 F1 FF FF FF F7 FF FF FF FF 3E C4 BC 2B 39 A4 e....... ..>..+9. 20CB C6D0: 8E 85 50 EB 7B 02 7B 93 79 77 50 EF 60 32 8C 03 ..P.{.{. ywP.`2..
4: 1F13 06B0: 00 00 01 E0 09 00 80 00 0D FF FF FF FF FF FF FF ........ ........ 1F13 06C0: FF FF FF FF FF FF 7F 5C 14 05 F2 9E 90 0F 6F A4 .......\ ......o. 1F13 06D0: B8 10 BF E9 6A 78 A3 00 13 00 FD 9C 00 A5 5B EB ....jx.. ......[.
1F13 06B0: 00 00 01 E0 09 00 80 00 0D FF FF FF FF FF FF FF ........ ........ 1F13 06C0: FF FF FF FF FF F7 7F 5C 14 05 F2 9E 90 0F 6F A4 .......\ ......o. 1F13 06D0: B8 10 BF E9 6A 78 A3 00 13 00 FD 9C 00 A5 5B EB ....jx.. ......[.
5: 1F13 06B0: 00 00 01 E0 09 00 80 00 0D FF FF FF FF FF FF FF ........ ........ 1F13 06C0: FF FF FF FF FF FF 7F 5C 14 05 F2 9E 90 0F 6F A4 .......\ ......o. 1F13 06D0: B8 10 BF E9 6A 78 A3 00 13 00 FD 9C 00 A5 5B EB ....jx.. ......[.
1F13 06B0: 00 00 01 E0 09 00 80 00 0D FF FF FF FF FF FF FF ........ ........ 1F13 06C0: FF FF FF FF FF F7 7F 5C 14 05 F2 9E 90 0F 6F A4 .......\ ......o. 1F13 06D0: B8 10 BF E9 6A 78 A3 00 13 00 FD 9C 00 A5 5B EB ....jx.. ......[.
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