Local Files in Wuala

Hello,
i dont understand the "local backup" thing 100%.

So my whole upload stuff is mirrored locally on my Harddisk?
Can i make exception or disable the "Localmirror-Feature"? I only can choose the direcotry, so my whole Upload is redundant on my own harddisk! (One time normal, and one time encoded at Local-Directory.

Thanks for your answer.