One of my absolute favorite features of Windows Server 2012 with Hyper-V is the VHDX disk file format. This new virtual disk format goes up to 64 TB and is the answer to many storage challenges for VMs when larger workloads end up as a VM.
While my virtualization practice frequently sees me leverage thin-provisioning, I don’t always make virtual disk files exactly to the maximum size they can be made. There isn’t too much harm in that point, unless the guest operating systems, of course, fill up. Monitoring discussions aside, there are situations where the VM will need its storage allocation increased.