[Debburn-devel] Bug: Can't put files bigger than 4GiB on disk

[Sven-Hendrik Haase]

On 22.10.2009 14:03, Sven-Hendrik Haase wrote:
> On 22.10.2009 12:33, Thomas Schmitt wrote:
>> Hi,
>>
>>   
>>> it appears there is a bug in the current cdrkit version that doesn't
>>> allow me to put files bigger than 4GiB on a disk. I tried calling
>>> mkisofs with
>>>
>>> -udf -allow-limited-size -iso-level 3
>>>
>>> Sadly, no success there, the files on disk remain unreadable. Am I doing
>>> anything wrong here or is it actually a bug?
>>>     
>>
>> Not knowing about genisoimage with large files
>> and especially not about -allow-limited-size,
>> i have to stress that in the past at least Linux
>> was not able to read files >= 4 GiB in ISO images
>> properly.
>> (Such files have to be split into several
>>  pieces, called "extents", and the reading system
>>  has to put them together.)
>>
>> Recent Linux kernels are said to work better.
>> Mine is of summer 2007 and cannot read some bytes
>> from the end of multi-extent files in images
>> created by libisofs. But users of recent Ubuntu
>> report that there are no problems any more.
>>
>>
>> man genisoimage says:
>>
>> -allow-limited-size
>>    ...
>>    The result is an inconsistent filesystem and users need
>>    to make sure that they really use UDF rather than ISO9660 driver
>>    to read a such disk.
>>
>> This sounds slightly frightening.
>> Maybe you should try without.
>>
>> If you are using Linux for reading:
>> Did you enforce mounting of UDF by mount -t udf ?
>>
>>
>> Have a nice day :)
>>
>> Thomas
>>
>>
>>   
>
> Actually it appears you guys are right. I just did some testing using
> a 10GiB file and I ran into no issues at all. The issue I reported was
> with a squashfs on an iso actually, so I tested 10GiB squashfs on iso
> and that was just fine as well. This magic might be explained by
> kernel 2.6.31 which came with some fixes that might concern this bug I
> experienced. I think for now we can consider this closed, sorry for
> the "false alarm".
>
> If I'm to run into this again, I'll revive this thread.
>
> -- Sven-Hendrik
> ------------------------------------------------------------------------
>
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I'd like to revive this issue because I have now found the real cause.
The problem is that genisoimage isn't able to generate a true
iso-level-3 image. It simply refuses to run when using a file that would
fill a DVD by itself (say, 4.3 GiB) and offers using udf instead. This
is wrong behavior since iso-level-3 can handle much larger files than
udf. I checked this against mkisofs from cdrtools and sure enough, that
one produces proper iso-level-3 images using large files. Can you guys
fix this in cdrkit?

-- Sven-Hendrik
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