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Gentree
Watchman
Joined: 01 Jul 2003
Posts: 5350
Location: France, Old Europe
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 Posted: Fri Apr 17, 2009 5:51 am Post subject: [SOLVED its a BUG] k3b burn does not match original |
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HI,
I have downloaded an iso image and burnt a copy with k3b with the verify option. It suceeds but tells me the new CD does not match the original.
I checked the md5 against the value on the server and it shows I got a good download. I have now burnt three copied on two different media types (CDR and CDRW). Exactly the same each time.
The live CDs boot and seem to function correctly (not a guarantee that they are perfect though) and I am wondering if this is not a fault in k3b.
FWIW the image in question is the unofficial minimal install CD
http://www.faskatech.net/latest/i686/installcd/install-i686-minimal-2008.0.iso
http://www.faskatech.net/reiser4-livecd/reiser4-download.html
After three burns it seems odd they all come out wrong. Any ideas what may be going on here?
TIA, Gentree. 
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Linux, because I'd rather own a free OS than steal one that's not worth paying for.
Gentoo because I'm a masochist
AthlonXP-M on A7N8X. Portage ~x86
Last edited by Gentree on Mon Apr 20, 2009 8:11 pm; edited 1 time in total |
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Sadako
Advocate
Joined: 05 Aug 2004
Posts: 3792
Location: sleeping in the bathtub
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| Posted: Fri Apr 17, 2009 6:28 am Post subject: |
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Run something like the following; | Code: | | dd if=/dev/sr0 bs=512 count=$(du --apparent-size --block-size 512 image.iso | cut -f1) | md5sum |
and see if that matches the checksum of "image.iso", the file you burned.
I believe cdrkit (or whatever) has a habit of burning a few additional bytes after the data it was asked to burn, and k3b includes that when verifying, which is what causes it to fail.
I think it's a known issue, and manually checksumming only the bytes which were supposed to be burned (like above) gives you a checksum matching the image.
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yabbadabbadont
Advocate
Joined: 14 Mar 2003
Posts: 4791
Location: 2 exits past crazy
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| Posted: Fri Apr 17, 2009 7:23 am Post subject: |
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Actually, k3b has been doing this on my machine for a while now. Don't worry about it, it is a false mismatch.
Also, you don't need to do anything fancy to check to see if they match, just run md5sum on the ISO, then run it on the device that is your cd/dvd burner.
Example: | Code: | md5sum mycdimage.iso
md5sum /dev/hdc |
If they match, you're good to go. They always do for me, even when k3b says that they don't... I just turned off the verify option in k3b. |
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Gentree
Watchman
Joined: 01 Jul 2003
Posts: 5350
Location: France, Old Europe
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| Posted: Sat Apr 18, 2009 7:06 pm Post subject: |
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| Code: | bash-4.0#md5sum /dev/hdd
84126f88f03b9fa428d286f303ffc80c /dev/hdd
bash-4.0#md5sum i*iso
84126f88f03b9fa428d286f303ffc80c install-i686-minimal-2008.0.iso
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thanks yabs , that's what I needed. Thanks hopeless for the explaination.
_________________
Linux, because I'd rather own a free OS than steal one that's not worth paying for.
Gentoo because I'm a masochist
AthlonXP-M on A7N8X. Portage ~x86 |
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lindegur
Apprentice
Joined: 14 Aug 2004
Posts: 292
Location: Swiss mountains
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| Posted: Sat Aug 08, 2009 9:31 am Post subject: |
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First thanks for the posts. I had some difficulties with k3b on one of my computers (It was not just k3b  ). It looks and I hope that (after some years  ) it is now solved  . I changed the DRAM latency setting in the BIOS from CL 2.5 to 3 what matches with the used DRAMs  . Since I got some corrupted backedup data, I is time for some tests:
| Code: | md5sum KNOPPIX_V5.3.1DVD-2008-03-26-EN.iso
4ccda04355e63d1485072f8906465168 KNOPPIX_V5.3.1DVD-2008-03-26-EN.iso |
this is what
| Code: | cat KNOPPIX_V5.3.1DVD-2008-03-26-EN.iso.md5
4ccda04355e63d1485072f8906465168 KNOPPIX_V5.3.1DVD-2008-03-26-EN.iso |
says, but when I do | Code: | md5sum /dev/hdc
85bb4695004e9edd52414f34a572eedb /dev/hdc |
I get an other checksum 
But finally | Code: | dd if=/dev/hdc bs=2k count=$(($(isosize /dev/hdc)/2048)) | md5sum
2171297+0 records in
2171297+0 records out
4446816256 bytes (4.4 GB) copied, 916.757 s, 4.9 MB/s
4ccda04355e63d1485072f8906465168 - |
gives the right checksum
What is going on with md5sum /dev/hdc 
Propably what Hopeless guessed, there is some additional stuff on the dvd
An other test, mounting the iso image via loop device:
| Code: | mount -o loop ~/knoppix/KNOPPIX_V5.3.1DVD-2008-03-26-EN.iso /mnt/loop
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and compare the files on the DVD with the files on the mounted loop device:
| Code: | | diff -qrd /media/KNOPPIX/ /mnt/loop/ |
No differences are reported, so the data is consistent |
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