LinuxQuestions.org
Go Job Hunting at the LQ Job Marketplace
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Software
User Name
Password
Linux - Software This forum is for Software issues.
Having a problem installing a new program? Want to know which application is best for the job? Post your question in this forum.

Notices



Reply
 
Search this Thread
Old 09-29-2004, 05:39 AM   #16
JZL240I-U
Senior Member
 
Registered: Apr 2003
Location: Germany
Distribution: openSuSE 13.1 / 12.3_64-KDE, Ubuntu 14.04, Fedora 20, Mint 17, Chakra
Posts: 3,689

Rep: Reputation: Disabled

Quote:
Originally posted by jimdaworm
...gave dd_rescue a go. Its pretty much the same as dd. It gets to the end and right near the end it gets errors
Sure, if you use it that way. But it can read "backwards". So, how close is it able to read to record 1333456 beginning to read from the end of the disk? In other words, how large is the gap of unreadeable data?

Or is record 1333456 in truth the end of the disk and something else is the problem (like a faulty fixating after burning or some such)?
 
Old 09-29-2004, 06:03 AM   #17
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Original Poster
Rep: Reputation: 30
I firstly tried the dd_rescue backwards and the errors came up straight away... what I thought is that as I know my hardware is fine, it must have been reading the wrong amount of of blocks form the cd so I used this script (as it was there)

Quote:
#!/bin/sh
device=$1

blocksize=`isoinfo -d -i $device | grep "^Logical block size is:" | cut -d " " -f 5`
if test "$blocksize" = ""; then
echo catdevice FATAL ERROR: Blank blocksize >&2
exit
fi

blockcount=`isoinfo -d -i $device | grep "^Volume size is:" | cut -d " " -f 4`
if test "$blockcount" = ""; then
echo catdevice FATAL ERROR: Blank blockcount >&2
exit
fi

command="dd if=$device bs=$blocksize count=$blockcount conv=notrunc,noerror"
echo "$command" >&2
$command
But the same thing happens... it gets to 339956 and says "Input/output error"


This is the output from Isoinfo:
Quote:
bash-2.05b$ isoinfo -d -i /dev/dvd
CD-ROM is in ISO 9660 format
System id: LINUX
Volume id: Slak10d2
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 2
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: 339984
Joliet with UCS level 3 found
Rock Ridge signatures version 1 found
bash-2.05b$

Last edited by jimdaworm; 09-29-2004 at 06:05 AM.
 
Old 09-29-2004, 06:09 AM   #18
JZL240I-U
Senior Member
 
Registered: Apr 2003
Location: Germany
Distribution: openSuSE 13.1 / 12.3_64-KDE, Ubuntu 14.04, Fedora 20, Mint 17, Chakra
Posts: 3,689

Rep: Reputation: Disabled
Hm, yes, I'm not that experienced in scripting, but that is not reading backwards if I understand it correctly.

And what about my two (three) questions?

<Edit>
I just noticed that you have the error now at 339956 which differs from the value you posted first. Does it change between runs of dd?

Last edited by JZL240I-U; 09-29-2004 at 06:24 AM.
 
Old 09-29-2004, 09:02 AM   #19
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Original Poster
Rep: Reputation: 30
Sorry JZL240I-U I wasn´t very clear on what I did. First of all I tried the dd_rescue in reverse mode (-r) and the errors came up straight away (So I guess its a problem reading the end of the cd)

Secondly I ran that script as it seemed like it would make sure that it read the right number of blocks

Quote:
I just noticed that you have the error now at 339956 which differs from the value you posted first. Does it change between runs of dd?
No I just ran it again to make sure but it gets to exactly the same spot. I even tried with my dvd writer and it gets to 339956 as well.

Quote:
how large is the gap of unreadeable data?
I guess what you mean is the difference between this:
Quote:
gets to 339956 and says "Input/output error
and this:
Quote:
Volume size is: 339984
By my calculations (Using my fingers) there is a difference of 28 (Blocks??)
 
Old 09-29-2004, 09:28 AM   #20
JZL240I-U
Senior Member
 
Registered: Apr 2003
Location: Germany
Distribution: openSuSE 13.1 / 12.3_64-KDE, Ubuntu 14.04, Fedora 20, Mint 17, Chakra
Posts: 3,689

Rep: Reputation: Disabled
Quote:
Originally posted by jimdaworm
...By my calculations (Using my fingers) there is a difference of 28 (Blocks??)
Poor dear, so you have 28 fingers ... what does the doctor say?

Well, so then you have to find out whether there are true data in those blocks or, as I noted above, whether there is the possibility of a faulty fixation. In both cases I think the prudent thing would be to get a new CD (and do a md5sum on it) and work from there...

BTW. is there a possibility that your downloads terminated jaust a little early due to some tight defaults (timeout or sóme such)?

Last edited by JZL240I-U; 09-29-2004 at 09:31 AM.
 
Old 09-29-2004, 11:42 AM   #21
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Original Poster
Rep: Reputation: 30
Doctor what doctor Hey I am not the only one with this problem I will have a search in a minute but there was someone else with the same problem. I can copy the windows xp cd and nfs2 cd without any problems I never get errors but with the slack cd I always do!
 
Old 09-29-2004, 05:16 PM   #22
DaneM
Member
 
Registered: Oct 2003
Location: Chico, CA, USA
Distribution: Linux Mint
Posts: 745

Rep: Reputation: 81
Thanks for the help everybody. I still haven't gotten it to work right but I have tried a few more things:

I booted into Windoze XP and used Nero 6 to copy the Slackware 10 install disks onto rewritables. I then booted back into Linux and tried to md5sum and dd them. I got the exact same results as I did with the originals, which makes me think that if Nero was successful at doing to copy then there must be some data on the original disks that's unreadable using normal means. It seems a lot like they're using some copy protection, but that would be pretty silly to do on GPL software. Nevertheless, just to see what would happen if it WERE using some kind of copy protection I tried doing dd and md5sum on a set of Doom 3 disks. Same results but the errors occurred earlier in the process. Very curious. Still, I seriously doubt that the Slackware guys would bother doing something so silly as preventing the disks from being copied. Just some thoughts.

--Dane

P.S. Has anybody else managed to copy the Slackware 10 disks? If so I'd like to know what you did to make it work. Also, which kernel is everybody using? I have a slight suspicion that this problem is specific to kernel 2.6.8 (which I'm using), although I don't have any real evidence to support it.

Last edited by DaneM; 09-29-2004 at 05:24 PM.
 
Old 09-29-2004, 09:48 PM   #23
95se
Member
 
Registered: Apr 2002
Location: Windsor, ON, CA
Distribution: Ubuntu
Posts: 740

Rep: Reputation: 32
Just a FYI, mkisofs can create bootable CDs. I had to use it to make some when creating a BSD iso. (for OpenBSD, it has instructions on the site, or somewhere)
 
Old 09-30-2004, 01:23 AM   #24
DaneM
Member
 
Registered: Oct 2003
Location: Chico, CA, USA
Distribution: Linux Mint
Posts: 745

Rep: Reputation: 81
Eurika! (...I think)

Hey everybody. I think I may have solved the problem, or at least on my computer. I was messing around with trying to burn another CD and realized that my CDRW was not using SCSI emulation, as seems to be recommended for cdrecord. I went online and learned that to enable SCSI emulation for that device I needed to add a bit like "hdc=ide-scsi" into my "append=" line in lilo.conf. The line now looks like:

append=" hdb=ide-scsi hdc=ide-scsi"

Now hdb and hdc (CDRW and DVD-ROM) are now /dev/sr0 and /dev/sr1, respectively. Cdrecord sees them as 0,0,0 and 1,0,0 respectively. Now I am able to dd and md5sum from either of those devices pretty reliably (although I still sometimes get I/O errors), and I've managed to make an image of Slackware 10 Install CD 1 and burn it onto a CDRW. Here's where things get weird.

The md5sum for the original CD is: 4edb29d05347a37f2ee64a80241f70ec
The md5sum for the image is: 2464f68acde7b4ad197e2a77a5ac5dc9
The md5sum for the new CD is: 4edb29d05347a37f2ee64a80241f70ec

Anybody notice anything fishy here? The original CD and the copy CD have the same md5sum but the image on my hard drive has a different one. Does this make any sense to anybody? The commands I used to do the copy are:

dane$ md5sum /dev/sr0

dane$ isoinfo /dev/sr0

dane$ dd if=/dev/sr0 of=Slak10d1.iso bs=<block size> count=<count> conv=notrunc,noerror

dane$ md5sum Slak10d1.iso

dane$ cdrecord dev=0,0,0 -pad -v -eject Slak10d1.iso

dane$ md5sum /dev/sr0

I appreciate everybody's help so far. Thanks.

--Dane
 
Old 09-30-2004, 03:33 AM   #25
JZL240I-U
Senior Member
 
Registered: Apr 2003
Location: Germany
Distribution: openSuSE 13.1 / 12.3_64-KDE, Ubuntu 14.04, Fedora 20, Mint 17, Chakra
Posts: 3,689

Rep: Reputation: Disabled
I think for getting a meaningful md5sum from your harddisk you will have to mount the iso9660 file as loop-back device (man mount). After all, you have a non-harddisk file system as an image on your real filesystem, that might very well cause disturbances...

As for the "solution", sorry but something is wrong here. Kernel 2.6.x has the scsi emulation included, so it should not be necessary and possibly even harmful to use it. It's certainly a workaround to do it this way but I think you should be very suspicious here...

Last edited by JZL240I-U; 09-30-2004 at 03:37 AM.
 
Old 09-30-2004, 04:34 AM   #26
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Original Poster
Rep: Reputation: 30
Just to confirm I am using Kernel 2.6.8.1 I might give that scsi emmulation work around a go.
 
Old 09-30-2004, 06:32 PM   #27
DaneM
Member
 
Registered: Oct 2003
Location: Chico, CA, USA
Distribution: Linux Mint
Posts: 745

Rep: Reputation: 81
I tried your suggestion and did:

dane$ mount -t iso9660 -o loop Slak10d1.iso /mnt/loop

dane$ md5sum /dev/loop0

and got the same md5sum as I got from the image file without mounting it. I'm not sure what you mean by SCSI emulation being built-into the kernel; for some reason cdrecord wouldn't pick up my devices until I enabled it in lilo.conf. Am I missing something? Also, although I can now md5sum and dd from the Slackware 10 CDs (albeit with some strange results), I just tried to do so from a Slax 4.1.4 CD that I made from an image and it was a no go--Input/Output error. You're right; the ide-scsi thing seems to help, but there's definately something wrong with my configuration still. Keep the ideas flowing :-) .

Have a good one.

--Dane
 
Old 10-01-2004, 03:14 AM   #28
JZL240I-U
Senior Member
 
Registered: Apr 2003
Location: Germany
Distribution: openSuSE 13.1 / 12.3_64-KDE, Ubuntu 14.04, Fedora 20, Mint 17, Chakra
Posts: 3,689

Rep: Reputation: Disabled
Quote:
Originally posted by DaneM
I tried your suggestion and ... got the same md5sum as I got from the image file without mounting it.
Well, I think it was worth a try ...

Quote:
Originally posted by DaneM
I'm not sure what you mean by SCSI emulation being built-into the kernel...
SCSI-access is now part of the kernel (as of kernel version >=2.6.0), at least that is what I read. Now, there might be some Slack-specific thingy here, maybe they load it as a module and your start up sequence doesn't do it (yet)? Dunno, I'm using SuSE, you might ask that in the Slack forum...

Don't forget to post the solution here.

Quote:
Originally posted by DaneM
Have a good one.
You too .

Last edited by JZL240I-U; 10-01-2004 at 05:37 AM.
 
Old 10-01-2004, 05:35 AM   #29
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Original Poster
Rep: Reputation: 30
2 more of my cents. Since I have been using 2.6.x kernels cd writing does work... although there seems to be something about it that cdrecord doesn´t like.

It works fine for me if I use cdecord /dev/hdc..... (but not the x.x.x) and when I set up xcdroast it always complains it can´t find ide-scsi and won´t find my drives, but If I manualy set them it works....

I guess there is something/some things that are not as up to date/compatable with built in kernel cd writing stuff.

 
Old 10-02-2004, 04:58 AM   #30
DaneM
Member
 
Registered: Oct 2003
Location: Chico, CA, USA
Distribution: Linux Mint
Posts: 745

Rep: Reputation: 81
I thought this was interesting...

I've been doing some more searching on the web about this issue and I found the following from a mempis.org forum:

Quote:
md5sum of a cd
Submitted by hard candy on Mon, 12/29/2003 - 14:15.
Once the iso is writen to a CD as a disc(not as an iso) it is possible to find the md5sum of the disc which will not be the same as the iso(after all it's not an iso now,merely the contents) but unfortuneatly they don't publish any md5sum of the CD which would be quick and simple so it's not going to be possible to check the sum against any known md5sum for the CD. More than you probably wanted to know but: To test a burnt cd: ls -ls .iso to find the filesize, in bytes, of the ISO image. Divide that by 2048 to find the number of sectorsxxxxxx). Put the CD into a drive but don't mount it. dd if=/dev/(x) bs=2048 count=(xxxxxx) | md5sum - where (x) is your device(eg. hdc, or scd0), where (xxxxxx) is the number of sectors. They should agree. Aside from all that-does the cd boot up correctly?
This seems to be saying that the md5sum of a cd can rightfully be different from the md5sum of its image on the hard drive. Can anybody confirm or deny this? Thanks again, everybody, for your help on this.

--Dane
 
  


Reply

Tags
burning, cd, dd, howto, image, iso


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
cdrom input/output error krystianownz Linux - Hardware 4 12-12-2007 12:19 PM
cp - error reading /mnt/cdrom/mpegav/avseq01.dat input/output error manishsingh4u Linux - General 2 10-17-2005 06:02 AM
cdrom input/output error HadesThunder Linux - Newbie 4 03-30-2004 05:57 PM
can anyone help, /dev/cdrom:input/output error mount speedyhot Linux - Newbie 3 03-01-2004 03:03 PM
Input/output error when reading from CD-RW drive vrooje Linux - Newbie 2 02-18-2004 12:17 AM


All times are GMT -5. The time now is 10:59 AM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration