VM disk larger than Unraid disk sizes

[pomtom44]

Hi all.

I have had a quick look into this, and believe It may not be doable based on what I have found, but safer just to ask to be sure.
 

At the moment my NAS is a windows box running storage spaces
Its not the most ideal and I wanted to move away from storage spaces.
however some software I run still needs to be run in windows, and it needs to be a local disk to work (can't be mapped network drives or symlink drives)

My way around this was to have unraid run as the "Raid" layer then install windows as a VM and mount virtual disks to unraid
I know its not the best solution, but its the only one I can find which works.

however I went to go set it up and while reading up on another problem I was having, stumbled into an issue I hadn't thought about
Most of my disks at the moment are small, 500gb for eg. where as my virtual disks are 2-4tb, so as far as unraid is concerned its a 4tb file.

It might be my misunderstanding of how unraid works, as I have been using storage spaces personally, and my job we had a proper SAN 
And both of these you just threw disks at it and created a virtual pool of space to use.
Where unraid seems to be using it disk by disk?

Am I missing something in setting up my unraid? or is this how it works?
 

[JorgeB]

Unraid array disks are independent filesystems, you could a use a multi-device pool, for now only btrfs is supported for those but soon zfs will also be supported.