VMware Cloud Foundation Architecture and Components
VMware Cloud Foundation is delivered as a VCF instance, and every architecture question resolves against one hierarchy: instance → domain → cluster → host. A domain contains exactly one vCenter Server and one NSX Manager cluster; a cluster contains ESXi hosts plus their principal storage. All vCenters in an instance are joined to a single vSphere SSO domain, which is what gives administrators one login and enhanced linked mode across domains.
Management domain vs workload domains
The first domain built is the management domain, and there is exactly one per instance. It hosts the infrastructure VMs: SDDC Manager, its vCenter, the three-node NSX Manager cluster, NSX Edge node(s), and the Aria/VCF operations and automation appliances. Workload domains carry tenant and application workloads - VI workload domains for vSphere plus vSAN, and Kubernetes-oriented domains in 5.x releases. SDDC Manager is the orchestrator and inventory of record. It is not in the data path: workloads keep running if it is down, but no day-2 automation does.
Traps
- NSX Edge clusters are not mandatory on every workload domain; NSX Manager is.
- The management domain's principal storage is vSAN - do not expect NFS or FC there.
- One SSO domain, many vCenters. Questions like to imply one SSO domain per workload domain.
- SDDC Manager does not configure the physical fabric; VLANs, MTU 9000 and routing are prerequisites.
- Licensing is applied per instance/domain in SDDC Manager, not inside each vCenter.
Rule of thumb
Size the management domain for the appliance tax: SDDC Manager, one vCenter, three NSX Managers, edge node(s) and the Aria nodes all consume the same cluster. Plan four or more hosts and confirm the current minimum in the design guide, because the management domain is the one domain you cannot rebuild cheaply.