Making Time Machine work with the ReadyNAS

Just a quick question, when I created the sparseundle i purposely left out a size determinate in the terminal command because I wanted to have the ability to have it grow exponentially without having to start over.

Time machine is working as expected (aside from a permissions error on the share after updating to latest firmware which I figured out) but by me creating a sparse bundle with no size requirements will it work in the way that I described? Or will at some random point the sparsebunle nuke itself and my backups into oblivion?

Thanks in advance.