Summary in advance: The ISO 9660 image aspects seem to be ok. Somehow the VM or the booted kernel decide that the emulated CD-ROM has only 500 MiB of read capacity.
I beg your pardon for all the fuss, but I've found the cause of this behavior. It turned out to be VirtualBox' fault. It was a mistake for me to turn on the option for using host I/O cache for IDE channel with CDROM. -- Eugene Paskevich | *==)----------- | Plug me into eugene@raptor.kiev.ua | -----------(==* | The Matrix