Okay, test DVD multi-session here, courtesy of Babbs:
http://puppy.wise-guy.us/
There's also a readme file.
Please heed the warning about the XP swap file.
I'm going to contact the author of growisofs, see if there is any way
to force only one track, instead of the two that are created on the DVD
-- which causes seek errors.
One really good thing is the efficiency of saved sessions, as all in track 2,
until dvd is full.
If you download usr_devx.sfs to /root, it will get saved to dvd at end
of session, then loaded back into /root next session and automatically
mounted on /usr.
...well, that was the idea, but after uploading the iso, i realised that
the shutdown cleanup moves it to /root/archive and it never gets
reloaded. Need to fix that.
However, if put usr_devx.sfs into /livecd, at shutdown there is an option
to create a new dvd, which will burn everything in /livecd onto the dvd,
as well as all files in /root, so the new dvd will load usr_devx.sfs
onto /usr at bootup ...again, in theory.