So, my question is : how to write large files on DVD (files > 2 GB).
I couldn't care less about k3b, take it up with their bugzilla if you
want, but first find out what mkisofs can do because k3b won't do more
than that. You can't portably put files >2GB on an iso9660 filesystem,
though newest mkisofs may be able to do it. If you just do backups for
yourself, portability isn't necessarily an issue. Try using udf instead
of iso9660, i.e. use -udf with mkisofs. Do some performance tests on
reading the files. It will store files >2GB, but it also loses a lot of
the file meta data (permissions, ownerships, ) and storing anything but
plain files may be risky. Beyond that, it's a pain. You could stream the
output of tar straight onto DVD, i.e. not use a filesystem at all.
Random access for reading isn't all that good, but it does store all the
data. Oh, multivolume and tar could turn into a pain. Whatever you do,
as always, test the backup can be properly restored...