How to burn Fedora DVDs to avoid readahead bug?
andre at bwh.harvard.edu
Tue May 8 06:37:50 UTC 2007
When I burned the Fedora ISOs to CDs, I used cdrecord with padding to
avoid the readahead bug - see
for how. In short, you use something like
cdrecord -v dev=/dev/cdrom -dao -pad padsize=63s FC-6-i386-disc1.iso
It turns out that the same precaution is necessary with DVDs, and until
recently I was able to use cdrecord for this, like
cdrecord -v dev=/dev/dvd -dao -pad padsize=63s FC-6-i386-DVD.iso
even though a lot of ugly-looking error messages appeared before the
burn commenced. But in the last month or so, instead of burning,
cdrecord simply gives up. See
I know about growisofs, but unfortunately it's incapable of putting
padding on the DVD _after_ the ISO file (I know it has a -pad option,
but it just passes it through to mkisofs, which provides padding
_inside_ the ISO, which isn't what is needed, and when burning an ISO
file it can't be used anyway). I tried once using dd to manually add
zero padding after the ISO, but although the resulting DVD passed
mediacheck, it failed to boot properly. So it seems that at the moment
there's no tool that can reliably burn a DVD and pad it properly. After
gradually learning over several years how to reliably burn Fedora ISOs,
I don't want to go back to mediacheck hell. As I see it, there are
1) Fix the readahead bug. Unfortunately, we all know that will never
happen. No one who's qualified cares enough to do it.
2) Fix cdrecord. The last time I successfully used it was March 29, so
some update since then broke it. It's not the kernel, since after
booting into the same kernel I was using then, it was still broken.
3) Find some other tool besides cdrecord that can do the necessary
padding for DVDs. Are there any?
4) Modify mediacheck. I know that by default mkisofs provides enough
padding to protect the files inside the ISO from the readahead bug. But
mediacheck is apparently checking the entire ISO, including the padded
part at the end after the actual files in it, where the readahead bug
occurs. Can it be tweaked to just check up to the end of the last file
inside the ISO? And can something similar be done so no errors occur
during the actual install either?
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