Frequent CD Integrity Check Errors (MD5)?

a49002 · 03-03-2007, 10:28 PM

Folks,

I am new(ish) to Linux/Ubuntu and have installed Edgy 6.10 ok. I have however had trouble on numerous occasions burning a CD that then passes the Ubuntu CDROM integrity check (at boot-up for a Ubuntu install). The Bit torrent MD5 value (in Azureus and uTorrent) of the downloading image matches the Bit torrent MD5 displayed at Ubuntu's Website, for the info hash value, not on the whole CD. Strangely, when I check the MD5 of the burned final CD the MD5 is never the same as that displayed on the Ubuntu Website, even when the Info hash is ok during download?

Anyway, I have tried two different PCs, Windows and Linux to download and burn and still i am often not successful at passing the Ubuntu CDROM integrity check? I have tried different media, slow burning speeds but I note from various forums that this is not an unusual situation.

My question is:

What is the most reliable way to download the ISO from a trusted site, check the MD5 value of that ISO, then burn this to CDR and test the MD5 for final verification before installation?

Many thanks for your time and assistance.

Paul

binary_y2k2 · 03-04-2007, 01:01 AM

How to check MD5sum on Linux and Windows
Also try not burning the disk at the highest speed of the writer, try a low speed instead.

win32sux · 03-04-2007, 02:12 AM

Quote:

Originally Posted by a49002

What is the most reliable way to download the ISO from a trusted site, check the MD5 value of that ISO, then burn this to CDR and test the MD5 for final verification before installation?

to download the ISO use anything you want... i use Firefox or wget or BitTorrent or whatever...

to check the downloaded ISO use md5sum, like:

Code:

win32sux@candystore:/home/win32sux/iso$ md5sum ubuntu-6.10-desktop-i386.iso
b950a4d7cf3151e5f213843e2ad77fe3  ubuntu-6.10-desktop-i386.iso

to burn the ISO to a a CD, use cdrecord, like:

Code:

cdrecord dev=/dev/cdrom speed=32 padsize=63s -pad -dao -v /home/win32sux/iso/ubuntu-6.10-desktop-i386.iso

to check the burnt CD, first find its logical block and volume size:

Code:

win32sux@candystore:~$ isoinfo -d -i /dev/cdrom
CD-ROM is in ISO 9660 format
System id: LINUX
Volume id: CDROM
Volume set id:
Publisher id:
Data preparer id:
Application id: MKISOFS ISO 9660/HFS FILESYSTEM BUILDER & CDRECORD CD-R/DVD CREATOR (C) 1993 E.YOUNGDALE (C) 1997 J.PEARSON/J.SCHILLING
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: 240523
Joliet with UCS level 3 found
Rock Ridge signatures version 1 found

then stick those numbers in your dd command, and pipe dd's output to md5sum, like:

Code:

dd if=/dev/cdrom bs=2048 count=240523 conv=notrunc,noerror | md5sum

ideally, the md5sum you get there (the CD "surface") will match the md5sum of the ISO...

interestingly, this is also how you'd make an ISO from the CD if you wanted to (you could then md5sum the new ISO, for example):

Code:

dd if=/dev/cdrom of=/tmp/ubuntu-cd-test.iso bs=2048 count=240523 conv=notrunc,noerror

a49002 · 03-04-2007, 10:03 PM

Quote:

Originally Posted by binary_y2k2

How to check MD5sum on.....
Also try not burning the disk at the highest speed of the writer, try a low speed instead.

Quote:

Originally Posted by win32sux

to download the ISO use anything you want... i use Firefox or wget or BitTorrent or whatever...

Many thanks indeed for both your replies.

Paul