MD5SUM errors with CentOS 4.6 when creating CDs and DVDs

Posted December 22nd, 2007 in Linux/Unix/BSD

When I downloaded the CentOS 4.6 ISO images they checksummed fine using MD5 checksums. When I burn them to CD or DVD the checkums of the disc itself do not match the actual MD5s. I have noticed this behaviour before with the CentOS 3.x and 4.x branch.

The actual MD5SUMs for CentOS 4.6 should look like this:

f253e3f4f816ea06c43eb39a595e9dbe  CentOS-4.6-i386-bin1of4.iso
f0ab4a6bc7b7d37087bacf5a10af5625  CentOS-4.6-i386-bin2of4.iso
8e23435398c4e1317d6611a2cda087ad  CentOS-4.6-i386-bin3of4.iso
690a444de101cfe3b0bd62f4f570020f  CentOS-4.6-i386-bin4of4.iso
15a1e531694952ae551f8fc6f1bc6ea1  CentOS-4.6-i386-binDVD.iso
f1b217dd0c37b7861fbdc889e8f3f943  CentOS-4.6-x86_64-bin1of4.iso
5e2b1ab88c64b52b142401abe353f8c4  CentOS-4.6-x86_64-bin2of4.iso
ff7bc2e579d50f18890b73344ae20890  CentOS-4.6-x86_64-bin3of4.iso
ba8b10fb2bab8f3644a2f4edd7e480a5  CentOS-4.6-x86_64-bin4of4.iso
a9392d1dc06610a144c855ae6250e95f  CentOS-4.6-x86_64-binDVD.iso

When I burn them to CD or DVD they look like this (I haven't yet had to burn the x86_64 CDs to disc; when I do I will update this post with them):

3b79cd621c46b4277465d23c4118917d  CentOS-4.6-i386-bin1of4.iso
6bd6f42a7d90885e89a131254c64a8f7  CentOS-4.6-i386-bin2of4.iso
8cf890b5888613e3c7bb1deace592dce  CentOS-4.6-i386-bin3of4.iso
b750b499387c2ddeb8e4231ae09ad342  CentOS-4.6-i386-bin4of4.iso
1ffa5680fd61fcabe5fa540825407354  CentOS-4.6-i386-binDVD.iso
f30eb920d8aea429e3a92f88f2b79fe7  CentOS-4.6-x86_64-binDVD.iso

I create a lot of CDs and DVDs for my Linux CD Mall website, and running a checksum after they have been burnt is extremely important to me to ensure they have been burnt correctly. This way I can be assured when I send an order out to my customers that the CD or DVD is a good one.

Fortunately, CentOS (like Red Hat Enterprise Linux, on which it is based, and also like Fedora) contains a disc checking function when you first boot into the installer. Whenever I have checksum issues after burning CentOS releases for the first time, I boot into the CD or DVD and run the disc checking utility. It has always reported the discs to be fine, and I have personally installed from these discs many times myself, so I know the burn is good.

It is also important to note that every time the disc is burnt I get the same MD5 checksum.

I do not know why the checksum from the burnt CD or DVD is different from the file MD5SUM, but fortunately the disc checking utility allows me to check the burn is actually good.