Can DLP servers run as VMs?
The number of physical servers depended on the number of your detection server.
You need 1 server to install Oracle and Enforce server. Then, you need 1 server to host the Network Monitor. You can deploy Endpoint Prevent and Endpoint Discover server into 1 physical server. And, you still need 1 server to host the Network Prevent for Email.
So, you will need 4 physical server to host all your available modules on your DLP license.
Can these 4 servers all be virtual machines all on one physical server instead needing 4 physical machines?