The script in

	<a href="http://mail-index.NetBSD.org/netbsd-users/2002/01/07/0000.html">http://mail-index.NetBSD.org/netbsd-users/2002/01/07/0000.html</a>

looks interesting.  I've been working on this problem myself (DVD+RW in my case).
However, I'd like to have dump itself do the volume splitting.

Dump records the volume number in the headers, and reports which inodes are
in which volume.  So if you know the inode you want to restore you can
go straight to the correct volume when restoring.   It appears to me that
the script referenced above would break this?

Also, if you have a bad piece of media, dump can ask you to change
the media and start that volume again without having to start the
entire dump over from the very beginning.

Another question is how does restore (or tar or whatever) know when
to stop reading data from a disk?  I've tried writing some data to
a dvd and when reading it back it just keeps going.  Does cdrecord
create something like a tape mark?