I have ~20TB that is currently mounted on a linux VM. Is it possible to have a Windows VM on the same host able to read that 20TB? It would have to be mounted directly on the windows VM (so not just a network share)
IMO no, you'll have to use a storage solution that supports simultaneous access (like you could find in network storage). If you mount the same disk to two VM you'll end up one day or another with corruption ... and well that's not great.