A provider virtual datacenter (Provider VDC) combines the compute and memory resources of a single vCenter Server resource pool with the storage resources of one or more storage policies created on that vCenter Server.
A typical vCloud Director system includes multiple Provider VDCs configured to meet various service level requirements. Each Provider VDC must be configured with a primary resource pool. Additional resource pools from the same vCenter Server can be added as needed. Non-primary resource pools can also be removed to free up vSphere resources for use in other Provider VDCs. The primary resource pool cannot be removed.
If you plan to add a resource pool that is part of a cluster that uses vSphere HA, make sure you are familiar with how vSphere HA calculates slot size. For more information about slot sizes and customizing vSphere HA behavior, see the VMware vSphere Availability Guide.