1) when Porteus is booted in "Always Fresh" mode then 60% of available memory is reserved for aufs (/ root). that means you can copy up to 600MB data to the system till your reach "out of space" message.
When you fill up aufs completely then 400MB is left for applications. if you copy only 200MB of data to the system then 800MB is available for use by apps.
2) when Porteus is booted in "Always Fresh' + "Copy2ram" cheatcodes then you have 600MB reserved for aufs minus size of actually used xzm modules. In case of filling up aufs completely there is always 400MB of RAM for use by the apps.
3) when Porteus is booted with "changes=partition/save.dat" then aufs size is the same as parition/save.dat and full 1GB of Ram is available for apps.
4) when Porteus is booted with "changes=partition/save.dat" + "Copy2ram" cheatcodes then aufs size is the same as parition/save.dat container and there is 1GB of Ram available for apps minus size of actually used xzm modules.
i hope it's not too complicated so far

Actual idea:
I'm thinking about mounting tmpfs in /tmp and /var/tmp folders when 'changes=' cheatcode is used.
this could be done by linuxrc during boot time - a proper info message could be displayed.
Adventages:
- faster KDE boot (LXDE boots fast enough so no benefit here). kde-4 creates few hundreds MB cache files in /var/tmp which could be done faster in RAM then in a save.dat file (usb sticks are rather slow in writing operations).
- faster work of all apps which keeps temporary files in /tmp folder
- less I/O operations on flash media which supposed to provide longer flash/ssd life (although i have read on aufs mailing list that Klaus Knopper could'n kill flash media in any way with hundreds of write operations, link:
http://sourceforge.net/mailarchive/mess ... d=28465723)
Disadventages:
- content of /tmp and /var/tmp folders is wiped off during every reboot so users must be remember to not keep any important data over there (who would keep them in /tmp folder??)
- 1GB of RAM available for apps is reduced by size of files which are kept in /tmp and /var/tmp folders.
My experience:
i'm doing this trick on gentoo box for very long time and can see only benefits. portage compilations are much faster when done in /tmp/portage folder (RAM) than on a hard drive.
Should i enable this feature for Porteus-1.1 or rather leave it as is?