nearly EVERY single iso image i have downloaded with http, ftp, and torrent always fail the md5 checksum. it seems to happen mostly with fedora core 9 dvd iso images. i've tried it on different computers and everything, and i've used multiple methods of checking.

the following have failed:

CentOS 5.1 DVD i386
CentOS 5.2 DVD i386
Ubuntu 8.04 DVD i386
OpenSuse10.3 DVD i386
OpenSuse 11.0 DVD i386
Fedora Core 9 DVD i386

they also fail media check in a virtual machine after mounting the iso image. any recommendations on how to get this correct??

I have tons of storage, 3g ram, 500GB hd, and a 10mb internet connection, you'd think that i'd be able to get atleast one image that works, but i cant!!

Thanks in advance.

Odds are that you either have a memory problem(ram) or a internet connection problem. The memory issue can be checked with memtest86(just Google it). Since you are seeing this across multiple distros I assume you are getting them from multiple sources. I would run a traceroute to Google and find the address of your last hop of your isp. Then do a ping -c 1000 and look at your packet loss.

also change the brand of dvd on some dvd drives brand A works but not brand B
on a diff machine it might be brand B that works
some times the VERY cheep disks will work for you
or the VERY Expensive $$$$$$ ones might work
also if the drive is old then it will be VERY fussy about the disks
and what are you using
dvd+r
dvd-r
dvd +rw
dvd +-rw
i prefer DVD+-RW even though the burn speed is x1 or x2

but I can download iso images for other apps with no issues. Like I stated before, I've tried on different computers, and have not burned them yet, just mounting the iso file in a virtual machine to do a media check.

thanks for the info!

Are your downloads going to (or being transferred to) a FAT filesystem such as external drive?

(In reply to response received via email):

FAT 32 filesystem has a limit of 4GB for a file, so a typical DVD iso will inevitably be corrupted if you download (or transfer from another local filesystem) the iso to a FAT 32 formatted drive. A lot of external drives come formatted FAT 32 because it is easily readable and writable by all kinds of OS (and FAT 32 doesn't support permissions).

If you need to use the drive with Windows or Mac as well you might prefer to use ntfs because ntfs-3g provides stable read/write capability and can be installed on Mac or any recent distro. If you exclusively use GNU/Linux then ext3 or one of the other native filesystems is a better choice.

there is one of the problems the .Sometimes the check sum will fail i had fedora 6 and 7 both fail that and fail the check during install . But the install went without a hitch .
Are you on the ( year 1996 ) FAT32 file system in win xp , some who upgraded win 98 to xp stayed in fat32.fat32 has a 4 gig max file size so a 4.2 gig iso WILL BE KILLED
http://support.microsoft.com/kb/314463
also for a new Linux user I would stay away from Fedora 9 and instead install fedora 8 , or Ubuntu . CentOS 5.1 is not bad but it is best suited for the office and for running a server ,where having it work is more important than having it run the NEW software. OpenSuse i have not ran it except for 2 weeks back in '06 so ?

You can do the checksum test by running the md[n]sum program on the iso image that you downloaded, without mounting the image (except the directory containing the image file, of course). Then compare the checksum produced with the expected value. (Note: the [n] in md[n]sum means "use the checksum program that the distributer used to generate the checksum that was published with the iso file.")

I suspect that the "virtual machine" you're using may be introducing discrepancies, and that actually burning the image file may give you a different check sum.

I run the checksums against the iso image alone. When I do a media check, i then mount the iso image into the virtmachine.

thanks for all the feedback.

Well, if the check of the ISO file, alone, is correct, the "media check" is not needed, so just skip it.

If I understood you correctly, the "media check" is looking at a mounted ISO image, not a "real" DVD drive, so I wouldn't be surprised that a check made when in "media" is not mounted as expected by the programmer fails.

The official Fedora ISO image checksums are SHA1 not MD5. You need to run "sha1sum" on them to calculate the checksums. Images downloaded from torrent are checked implicitly by the download client.