[Unionfs] How to synchronized some filesystems merged with unionfs

[Sylvain Ferrand]

Hi,

I'm  designing an embedded system with a read-only root(/) file
system (a compact flash) combined to a writable tmpfs branch.
It works very well, but from time to time, I would like to be able to 
sync the tmpfs branch with the compact flash partition (to save changes 
made to the system).
Do you have simples procedures to do that? I'm thinking about to create 
a special partition and to copy the content of the tmpfs branch on it 
and later to synchronize during the reboot.
I'm interested about any ideas or links to articles to do that.
Thanks,

Sylvain