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olias2
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Joined: 23 Aug 2003
Posts: 234
Location: CANADA
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 Posted: Wed Nov 17, 2004 3:35 am Post subject: cdrecord - CD Exact Copy? |
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I'm trying to learn the Linux way and was wondering if I did it right. I wanted to make a backup of a CD so I made a /etc/default/cdrecord file with the following entries in it...CDR_DEVICE=/dev/cdrom
CDR_SPEED=24
Then I logged in as 'su' and entered the following... | Code: | | dd if=/dev/cdrom of=/tmp/myCD.iso |
swapped in a blank CD...
| Code: | cdrecord -v /tmp/myCD.iso
rm /tmp/myCD.iso |
It made a working copy but I don't know if it's exact. Any advice would be appreciated.
Thanks, Olias
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lost+found
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Joined: 15 Nov 2004
Posts: 509
Location: North~Sea~Coa~s~~t~~~
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| Posted: Wed Nov 17, 2004 10:41 pm Post subject: |
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I'm using Arson for copying, which uses cdrdao. But don't know about a Nero-like check function...
If you make an ISO image from the copy, it must have the same md5sum as the other ISO image. Then both cd's are identical. Well, maybe it's only proof that the copy is identical to the image of the original... :-(
| Code: | # md5sum /tmp/myCD.iso
# dd if=/dev/cdrw of=/tmp/myCD2.iso
# md5sum /tmp/myCD2.iso |
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olias2
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Joined: 23 Aug 2003
Posts: 234
Location: CANADA
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| Posted: Thu Nov 18, 2004 12:02 am Post subject: |
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Thanks L&F for the tip. I think it will come in handy.
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adsmith
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Joined: 26 Sep 2004
Posts: 1386
Location: NC, USA
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| Posted: Thu Nov 18, 2004 12:17 am Post subject: |
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| sure, or cat /dev/cdrom > /tmp/image.iso instead of your dd command. |
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lost+found
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Joined: 15 Nov 2004
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Location: North~Sea~Coa~s~~t~~~
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| Posted: Thu Nov 18, 2004 9:24 am Post subject: |
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Maybe this is running smooth:
| Code: | # cat /dev/cdrom | md5sum
# cat /dev/cdrw | md5sum |
Making the image with dd (and burn it) and checking with cat both cd's, will make the check 100%.
If there's nothing wrong with checking this way, I think it's worth to make a simple script! 
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Regrds. |
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lost+found
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Joined: 15 Nov 2004
Posts: 509
Location: North~Sea~Coa~s~~t~~~
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| Posted: Mon Nov 22, 2004 10:09 am Post subject: |
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With some cd's I get an error...
| Code: | # cat /dev/cdrom | md5sum
cat: /dev/cdrom: Input/output error
738943f26723b8140c9ef7561ea01e80 - |
I guess it's because some cd's have a bad sector at the end (saw this with IsoBuster), although it never seems to affect the last file on the cd. Does somebody know what this could be?
Running the check with a lower priority is a little bit better in those cases, because it eats a lot of cpu for a while.
| Code: | | # nice cat /dev/cdrom | md5sum |
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adsmith
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Joined: 26 Sep 2004
Posts: 1386
Location: NC, USA
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| Posted: Mon Nov 22, 2004 12:27 pm Post subject: |
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| I'm not sure why, but I often have this same "problem"... it also seems related to which drive I'm using. |
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Ambys Shrink
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Joined: 13 Nov 2004
Posts: 33
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| Posted: Tue Nov 23, 2004 11:29 pm Post subject: |
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| lost+found wrote: | | If you make an ISO image from the copy, it must have the same md5sum as the other ISO image. |
The problem with this is that ISO files contain extra data (much like some wave files), and so two identical ISO files (data-wise) may yield different MD5's due to timestamps (much like wave files can in the same way). We've had this problem creating torrents of DVD's at www.tunesonthemove.net (legal ones of course!) via ISO because when seeders hop on, the ISO's are all different because it depends on the software used to "Rip" the ISO.
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AIM: Ambys Shrink
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lost+found
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| Posted: Wed Nov 24, 2004 1:01 pm Post subject: |
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@adsmith
Here the same: one SCSI CD-RW (old one), and only the IDE DVD-ROM reporting read errors sometimes...
@Ambys Shrink
Yes, I think it must be done with the raw data, checked on the same machine. |
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