In Cloud Foundation, a workload domains is a policy based resource construct with specific availability and performance attributes. It combines compute (vSphere), storage (vSAN), networking (NSX-T Data Center), and cloud management (vRealize Suite) into a single consumable entity. for creating logical pools across compute, storage, and networking. A workload domain consists of one or more vSphere clusters, provisioned automatically by SDDC Manager.
There are two types of workload domains - the management domain and VI workload domains.
The management domain is created during the bring-up process. It contains the Cloud Foundation management components. This includes an instance of vCenter Server and a three-node NSX Manager cluster for the management domain. The management domain uses vSAN storage.
You can create Virtual Infrastructure (VI) workload domains for user workloads. For each VI workload domain, you can choose the storage option (vSAN, NFS, or VMFS on FC). A VI workload domain can consist of one or more vSphere clusters. Each cluster starts with a minimum of three hosts and can scale up to the vSphere maximum of 64 hosts. SDDC Manager automates creation of the workload domain and the underlying vSphere cluster(s).
For the first VI workload domain in your environment, SDDC Manager deploys a vCenter Server and an NSX Manager cluster in the management domain. For each subsequent VI workload domain, SDDC Manager deploys an additional vCenter Server. New VI workload domains can share the same NSX Manager cluster as an existing VI workload domain, or deploy a new NSX Manager cluster. VI workload domains cannot share the management domain NSX Manager cluster.