vCenter provides a number of services and interfaces, including:
The figure below clarifies the organization of vCenter services within the vSphere environment.
Figure 25. vCenter services
The Platform Services Controller (PSC) can be deployed as either embedded (in externally hosted vCenter) or external, as shown below. When VxRail-hosts vCenter the PSC is deployed external as a separate VM. See the figure below.
Figure 26. Embedded and external PCS deployments
Embedded PSC is ideal for small environments, or if simplicity and reduced resource utilization are key factors for the environment. The vCenter Server is bundled with an embedded PSC, and all the PSC services reside on the same host machine as vCenter Server.
External PSC (see the figure below) is ideal for larger environments, where there are multiple vCenter servers, but you want a single pane-of-glass for the site. The services bundled with the PSC and vCenter Server are deployed on different virtual machines or even different physical servers. When utilizing an externally hosted vCenter with external PSC, Enhanced Linked Mode (ELM) is supported.
Figure 27. External PSCs configured for high availability