You could set it up to expand if it hits some low disk space threshold

That’s a good idea, I can be proactive about some things, e.g. it won’t get suddenly more than 30GB of data, so I could maybe resize it once the free space is ~50GB. I’ll look into it, thanks!

The problem aren’t the steps involved but the manual vs automatic side of the resizing. E.g. the partition inside the vm is full and a user tries to send a big file, is it easy to automate the resize of the partition so that the file can fit? If it requires manual intervention I can’t use this solution.

I think that the qcow2 image doesn’t have to be resized manually; only the partition inside it. When you create the image the size you specify is the max size it is allowed to reach. When I first tried this, I created a max-2TB image, the actual size of the image was 200KB.

There is no need to move the VM nor a need to create many VMs-qcow2 storage images so I guess I can stick with 4.

The need is to easily redeploy the VM if needed (its / is a different drive than the storage one) and access the files inside the storage drive without hassle. So if I stay with 4 I can redeploy the VM, attach the qcow2 image and restore the fileserver to its pre-redeployment state.