CD-ROMs with deep directory structure?

From: Marko Mäkelä (
Date: 1998-08-05 22:40:24

This is a bit off-topic question, but I think that the chances of getting
an answer are better here than in a high-traffic newsgroup.

I'm preparing some CDs of the files in's /pub/cbm and
/pub/cpm sections.  I'm pretty new to the CD burning business, but I've
made some CD images with mkhybrid on Linux and examined them by mounting
them through the loopback device.  Today I got the first CD burned.  It
works fine when Rock Ridge a.k.a. High Sierra extensions are enabled, and
the long file names are available also in Windows NT, thanks to the Joliet

In systems not supporting either extension (e.g. MS-DOS), the file names
are short, and the TRANS.TBL file (created by the mkisofs -T option) can
provide some aid. But the index.html files won't work.  I already have a
workaround for that: I'll write new versions of and that will create index.htm, ALLFILES.htm and ALLDIRS.htm
files with links for the short file names.

There is still one problem: The ISO 9660 standard doesn't allow more than
8 levels of subdirectory nesting.  By default, mkisofs and mkhybrid
relocate directories that go deeper than this.  With Rock Ridge
extensions, this is transparent.  But in Joliet and in bare ISO 9660, the
subdirectories that would go too deep are replaced by zero-length files,
and the directories can only be found from somewhere under the rr_moved
directory off the root directory.  The new location is not reported
anywhere, but it seems that the directory appears directly in /rr_moved.
Luckily no directory is nested deeper than 16 levels, and there aren't any
duplicate names in /rr_moved.

In the mkisofs/mkhybrid man page the -D switch is documented as follows: 

       -D     Do  not  use deep directory relocation, and instead
              just pack them in the way we see them.   This  vio­
              lates  the  ISO9660  standard, but it works on many
              systems.  Use with caution.

And here's my question: Does anyone know which systems have problems when
the subdirectories on a CD-ROM are nested more than 8 levels?  Or which
systems (in addition to Linux) don't have any problems?

When these problems are solved, I will write instructions how to create CD
images from the files in /pub/cbm and /pub/cpm, including HTML files that
ease browsing.  I won't prepare or distribute such CDs myself, because I
don't have the equipment (not even a CD-ROM drive in my home computer) or
the time to do it, but instead I encourage others to do so.  I think that
several hundreds of copies could easily be sold.  I'd appreciate it if
anyone distributing the CDs gave me some feedback about the number of sold
copies.  It would give a rough (under)estimate of the number of active
8-bit Commodore users. 


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