On the fly JBOD

I'm not too sure about JBOD, but I want to be able to add new disks as
the drives fill up. I know its possible to mount Disks as folders, but I
want the convince of being able to use the array as a single, expanding
drive (one drive letter and no folders, just files). I'm also hoping its
very easy to continue work if one drive in the middle of the array