If your trying to understand how their parity drive works, this is a start
With links to deeper discussions.
You would have a large data pool, with 1 folder structure.
To be honest if what your looking for is folder structure and ease of access - what does it matter what the filesystem is or standalone on multiple disks vs striped across. I would worry about striping across spindles for performance. But if performance is not of primary concern, to be honest the tech used to provide you with your 1 common folder structure should be of secondary importance.
I fully agree with understanding the tech, at least at a basic level before using it. But its really not all that different than parity in a normal striped raid setup like 5. Just that the parity is stored on 1 drive vs stripped across all of them in the array.
One of the cool things about it and some of the other options, is that unlike with a typical raid where parity has to be created on the fly when you write the file. With unraid the parity can be created in the background after the fact for performance increase with the use of a cache drive. And my other below options also have ability to not have to do realtime parity creation.
I was a couple of minutes a way from going with unraid on the N40L, and even running it as a VM just like doing with my current setup. But the ability of the drivepool addon to add my existing data into the pool without having to wipe drives pushed me to go my current route. As long as I can have duplication of specific data that I don't want to have to recover from backup on a loss its a win win for me.
I get my common folder structure that spans the multiple drives for ease of use. I have a media folder, and then under that subfolders for tv/movies/music/etc -- I don't really care what filesystem its on. What is nice with this setup as well - is if need be I can directly access the files off the disks on any system that can read NTFS - with same folder structure and names.
My point being is I would expand your view of what is available - and not get stuck using the old standard raids and methods of file storage/parity and access.
If your priority is ease of file management (folder structure) and ease of expandability and ability to use nonlike drives I would look to some of the newer methods vs just plain jane raid 5. I have been very impressed with using the drivepool on my windows based server - you can use WHS if you want.
Other options that will work on just plain server or desktop version of windows is http://snapraid.sourceforge.net/
(free) another is http://www.flexraid.com/
There are other things to look today other just standard raid 5 - that is for damn sure! Expanding your options is always a good thing!
All that being said if you want to stick with 5, there are cards out there even on soho budget that allow for expansion of the array on the fly. The intel matrix storage stuff is pretty freaking slick for example