How to burn Fedora DVDs to avoid readahead bug?

[Andre Robatino]

Rick Stevens wrote:
> On Tue, 2007-05-08 at 02:37 -0400, Andre Robatino wrote:
>   
>>   When I burned the Fedora ISOs to CDs, I used cdrecord with padding to 
>> avoid the readahead bug - see
>>
>> http://www.troubleshooters.com/linux/coasterless.htm
>>
>> 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
>>
>> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=233745
>>
>> 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 
>> several options:
>>
>> 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?
>>     
>
> All of my FC DVDs have been written with:
>
> 	growisofs -dvd-compat -Z /dev/dvd=/path/to/dvd.iso
>
> with nary a glitch (no need for read ahead padding, nada).  Burned on
> multiple machines with different DVD writers, readers, etc.  Either I've
> been hugely lucky or you've been hugely unlucky.
>
>   
  You've been lucky.  I have two DVD burners, a Mad Dog MD-8XDVD9 bought 
3 years ago which is vulnerable to the mediacheck bug, and a Sony 
DRU-120C bought a few months ago which doesn't appear to be (although I 
haven't had it long enough to be sure).  It's possible that on average 
DVD drives are less likely to be vulnerable than CD drives used to be.  
I know the problem exists when burning DVD+RW discs without padding.  
IIRC, a DVD+R disc I burned without padding didn't appear to have the 
problem even on the vulnerable drive, but I'd rather use the padding to 
be sure.