Including the chunks that don't have any data I care about on them.
So, back to my original question, if I mount the drive, then tar it up, then unmount, then at some later date go back and remount the drive, and untar everything back on to it, it should pick up exactly where it left off, no?
Basically, what I've got is a dual-boot machine with three hard drives:
HDA - <whatever>
HDB - Debian
HDC - Storage space
I want to back up HDA's file system at various intervals, then restore it when I'm done screwing around to an earlier version. Saving disk space would be nice as well.