Hi utu,

Figured out what's going on here yet ?

While Knoppix is running, you've got a unionfs that comprises two halves - the read-only /KNOPPIX and the read/write /KNOPPIX-DATA. When you unzip your update tar file, where do you think the files in it go ? Into the empty /KNOPPIX-DATA of course and the backing store for that in your knoppix-data.img. So you end up back where you started. I don't think that is quite what you were trying to do.

You expressed surprise that you could delete you update tar file after first use. Actually you need to do this. Suppose you've tweaked Iceweasel and you've backed those tweaks up in your update tar file. First reboot, Knoppix will unpack the files in your update tar file so restoring your tweaks. Now suppose you tweak Iceweasol some more. You reboot without generating a new update tar file and without deleting the old one. Oops, Knoppix will unpack the files ... most probably obliterating your new tweaks. I imagine this would quickly become tedious.

Potentially worse is that you save to your tar file /KNOPPIX-DATA but Knoppix restores to /UNIONFS. Suppose you delete a package. It's not really gone. The UNIONFS writes a bunch of 'white out' files to the UNIONFS. When you tar up /KNOPPIX-DATA, you tar up all the white out files and any other hidden control files put there by aufs. When Knoppix applies your update tar file, it try to apply the white out files as if they were ordinary hidden file of no significant to aufs. A source of instability in the file system ? I don't think so, I think aufs will refuse to write such files to the UNIONFS and you'd get a bunch of error messages. The result is the deleted package reappears but may well be broken. This too could get tedious. As dinosep will tell you, deleted files should stay deleted.

Anyway, have a look at this post: http://www.knoppix.net/forum/threads...ersistent-data. This is not quite what you've been trying to achieve but it might be good enough for now.