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Old 10-02-2004, 04:20 PM   #31
kilgoretrout
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They match if you use that rawrite script I gave in my original post. I've done it many times.
 
Old 10-02-2004, 06:40 PM   #32
mritch
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have you already tried the prog "readcd". there is an option to ignore read errors - i once burned a protected cd and it worked ok (eg. copied the "bad"sectors to the image/cd).

(ignore this if it was mentioned already - i didn't read all the posts)
sl mritch.
 
Old 10-13-2004, 06:16 PM   #33
DaneM
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I found a thread on groups.google.com that seems to explain a lot. It seems to point out that any CDs that aren't burned using DAO will produce input/output errors when trying to read to an image or md5sum under Linux. Here's the link:

http://groups.google.com/groups?hl=e...gov%26rnum%3D4

The author, after using many unsuccessful methods, demonstrates the proper way to burn a CD from the image file. I've tested both the incorrect methods and the correct methods and from what I can tell he's right. I was finally able to make a good burn of Dynebolic 1.2 by using his method, after several unsuccessful burns using other methods. Perhaps the Slackware CDs we have were burned using TAO?

I came across another thread that verify what mritch said about it being better to use readcd than DD to make the images. Still working on verifying it myself.

I hope this helps.

--Dane
 
Old 10-15-2004, 03:29 AM   #34
DaneM
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I found a workaround if anybody's interested:

Taking ebel's advice I proceeded to bullheadedly persist at trying to make it work, and after a few weeks I eventually worked out a system that gave me some bona-fide slackware ISOs from the CDs I got in the mail.

One thing that I found quite troublesome is that doing "md5sum /dev/sr0" produces incorrect results, and different incorrect results almost every time (when it works). (My cd burner is /dev/sr0.) The correct way to get an md5sum from the cd is to do:

Code:
[dane@Orchestrator Slackware]$ isoinfo -d -i /dev/sr0
CD-ROM is in ISO 9660 format
System id: LINUX
Volume id: Slak10d1
Volume set id:
Publisher id: Slackware Linux, Inc. <info@slackware.com>
Data preparer id: Slackware Linux, Inc. <info@slackware.com>
Application id: Slackware Linux 10.0 disc 1
Copyright File id:
Abstract File id:
Bibliographic File id:
Volume set size is: 1
Volume set sequence number is: 1
Logical block size is: 2048
Volume size is: 333408
Joliet with UCS level 3 found
Rock Ridge signatures version 1 found

[dane@Orchestrator Slackware10]$ dd if=/dev/sr0 bs=2048 count=333408 conv=notrunc,noerror,sync | md5sum
333408+0 records in
333408+0 records out
2464f68acde7b4ad197e2a77a5ac5dc9  -
Now create the image by typing:

Code:
[dane@Orchestrator Slackware10]$ dd if=/dev/sr0 of=Slack10d1.iso bs=2048 count=332144 conv=notrunc,noerror,sync
333408+0 records in
333408+0 records out
Finally, make sure that the image matches the original CD by typing:

Code:
md5sum Slack10d1.iso
If the resulting md5sum matches the one from the CD, then you have a good image. Now you can make some copies of the CD.

Note: If you're using a CD-RW be sure to do a "cdrecord dev=0,0,0 -v blank=all" (assuming your device's SCSI address is 0,0,0). Otherwise when you check it against the original you could end up md5summing a bunch of data from your previous burn on that disk.

Also note: the reason you've been having "input/output" errors while trying to get an image off of the original CD is because the person who created it neglected to "pad" it properly when burning it in TAO mode. This makes it act up on Linux systems because of the "readahead bug" mentioned in a previous post. Also see the cdrecord manual page. Adding either (but not both) "-pad" or "-dao" to your cdrecord command will fix this. Following the instructions below will make sure that your new CD won't have the same problems.

Now pop in a blank CD and do:

Code:
cdrecord dev=0,0,0 -v -pad driveropts=burnfree Slack10d1.iso
Note that this command assumes that your drive is SCSI device 0,0,0 and that it can do burnfree.

Finally, test this new CD against the old one by doing:

Code:
dd if=/dev/sr0 bs=2048 count=333408 conv=notrunc,noerror,sync | md5sum
If the md5sums match, then you have a winner! Now just burn the other 3 disks and give copies to everybody you know who you think needs a little SLACK. (www.subgenius.com)

Note: Keep in mind to check the block size and count for every CD; don't just copy and paste the commands above for disks 2-4!

Good luck everybody!

--Dane

Last edited by DaneM; 10-24-2006 at 09:54 PM.
 
Old 10-15-2004, 03:43 AM   #35
jimdaworm
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Its cool to hear it sounds like you have it all sorted but its a bit of a shame that it has to be done with scsi emmulation and its sooo much work just to copy a cd!!! In your opinion is it dd fault?? or of the 2.6.x kernels???
 
Old 10-15-2004, 03:54 AM   #36
JZL240I-U
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He already said it: "...the reason you've been having "input/output" errors while trying to get an image off of the original CD is because the person who created it neglected to "pad" it properly when burning it in TAO mode. This makes it act up on Linux systems because of the "readahead bug" mentioned in a previous post...". But you are right inasmuch the oroginal author might have got a warning by the software he used...

BTW: respect and kudos to DaneM for solving this . Well done, correct procedure duly noted , though I still think that "rawread" at http://troubleshooters.a3b3.com/linux/coasterless.htm should have worked as well...

<edit>URL corrected...

Last edited by JZL240I-U; 10-15-2004 at 04:03 AM.
 
Old 10-15-2004, 04:00 AM   #37
DaneM
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Thanks a bunch!

Right, jimdaworm, it's a whole lot of work just to burn a CD, but I must say, I've never been so happy to finish a burn in my life!

*does the happy dance*

Have a good one.

--Dane
 
Old 10-15-2004, 04:09 AM   #38
JZL240I-U
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Hey, you are up early in Ohio, doing a dance in the morning like this ... or is it a late-late shift for you...

<edit>Hm, it's Chico, California, not Ohio ... did I misread or did you move?

Last edited by JZL240I-U; 02-24-2005 at 02:18 AM.
 
Old 10-15-2004, 06:02 AM   #39
jimdaworm
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@JZL240I-U what I ment is why does scsi emmulation have to be used?? Because of a kernel problem or because of a dd fault??
 
Old 10-15-2004, 06:26 AM   #40
JZL240I-U
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The kernel had up to and including the 2.4.x series no ATAPI-interface, thus you had to emulate SCSI-access for the ATAPI-devices ... (the 2.6.y series has remedied this). It's not a bug and has nothing to do with dd per se. There is a bug though as referred to in the man cdrecord pages: "... Use this option if your CD-drive is not able to read the last sectors of a track or if you want to be able to read the CD on a Linux system with the ISO-9660 filesystem read ahead bug. "

I DO recommend reading up the site DaneM referenced and also (again...) http://troubleshooters.a3b3.com/linux/coasterless.htm .

Last edited by JZL240I-U; 10-15-2004 at 06:27 AM.
 
Old 02-24-2005, 02:06 AM   #41
DaneM
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Update

I just thought I'd toss in one more pointer: using "conv=notrunc,noerror,sync " has proven very reliable even on my more cantankerous DVD/CD drive for getting a reliable MD5sum or image rip.

Have fun!

--Dane

Edit: Included in my "HowTo" on the previous page.

Last edited by DaneM; 06-23-2006 at 05:36 PM.
 
Old 10-24-2006, 08:18 PM   #42
twelvenine
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is there a reason that you used 332114 as the count in dd? did you mean 333408, since that was the iso volume size?
 
Old 10-24-2006, 09:55 PM   #43
DaneM
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That was a typo; thanks for pointing it out. I've changed the post for correctness.

--Dane
 
Old 10-24-2006, 10:49 PM   #44
twelvenine
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i burned a livelinux cd yesterday and i'm trying to verify that it has the right md5. i'm sure that it was burned with tao because i just burned it real fast with: 'cdrecord dev=ATAPI:0,0,0 speed=8 -v -data image.iso', i didn't use -pad or -dao. but, when i try to use dd to grab the image of it with: 'dd if=/dev/hdc of=check.iso bs=2048 count=301135 conv=notrunc,noerror,sync', dd has lots of i/o errors and the md5 of check.iso is not equal to the original iso.

the reason that you were able to get images from those slack discs without i/o errors from dd was that you had dd ignore the padded area, which was causing the problem, right? so i shouldn't i be able to get a decent image of my unpadded disk if i do the same?
 
Old 10-25-2006, 12:01 AM   #45
DaneM
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Hmmmm...the command that you're using looks good. Please post the output of "isoinfo -d -i /dev/<cddrive>" with the CD in the drive. Make sure that you've typed in all the numbers correctly.

Also, are you using high-quality media? Some brands of CDs work better than others for certain drives.

Can you read the CD in Windows (assuming you have a Windows installation)? Do the files show up when you mount the disk?

It could just be that since you didn't follow the instructions above, you have created a CD that won't work properly under Linux, or perhaps even at all. Please post answers to the above questions and I'll try to help you solve the problem.

--Dane
 
  


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