Portable backups?

[Romain Kang]

Does anyone have a recommended solution (or one that works, period) for
generating backups that work between Linux and OS X?  One of my friends
is banging his head against this conundrum at the moment:

	I can't use the finder/hdiutil because it doesn't preserve
	permissions, doesn't work on UNIX system directories, and
	yields a CD-R that cannot be read by anything but another
	Mac. I can't use tar because it doesn't preserve the resource
	fork. I can't use mkisofs because it does not preserve
	permissions, truncates names at 32 characters, and seems
	to have bugs that prevent it's CD-R's from being read
	correctly. And dump doesn't work on HFS+ at all.

Romain