We use HP Blade server architecture with virtualization on Microsoft Hyper-V in our datacenter. All virtual servers run both on NTFS and CSV (Clustered Shared Volumes) to have optimum advantage of Microsoft Clustering.
On the RAM and CPU limits of the virtual machines, new virtual machines are added into the farm with with Live Migration technology. Below is the farm topolgy we use in our primary datacenter. For disaster recovery, we have a backup datacenter in another location 500 km far from the main DC.
