Both physical and virtual vCenter Server installations are compatible.
Migrating to VCSA involves the deployment of a new appliance and migration of all configuration (including distributed switches) and historical data using the upgrade installer.
The appliance also saves operating system license costs and is quicker and easier to deploy and patch.
Features such as Update Manager are bundled into the VCSA, as well as file based backup and restore, and vCenter High Availability. A couple of releases ago the VCSA reached feature parity with its Windows counterpart, and is now the preferred deployment method for vCenter Server. The VCSA scales up to 2000 hosts and 35,000 virtual machines.
Furthermore the embedded vPostgres database means VMware have full control of the software stack, resulting in significant optimisation for vSphere environments and quicker release of security patches and bug fixes. Since the OS has been developed by VMware it benefits from enhanced performance and boot times over the previous Linux based appliance. The VCSA is a pre-configured virtual appliance built on Project Photon OS.
VCenter 6.7: Download | Release Notes | What’s New | VMware Docs | vSphere Central About VCSA This post gives a walk through on migrating from a Windows based vCenter Server (VCS) to the Photon OS based vCenter Server Appliance (VCSA). All future releases will only be available as vCenter Server Appliance (VCSA) which is the preferred deployment method of vCenter Server. It should be noted that vCenter 6.7 is the final release where Windows modules will be available, see here for more information. The vCenter Server is a centralised management application and can be deployed as a virtual appliance or Windows machine. VMware vCenter Server pools ESXi host resources to provide a rich feature set delivering high availability and fault tolerance to virtual machines. The vCenter HA summary page is displayed with a list of prerequisites, ensure these are met along with the requirements above.
Log into the vSphere client and select the top level vCenter Server in the inventory. If you are configuring vCenter HA in a cluster with less than the required number of physical hosts, such as in a home lab, you can add a parameter to override the anti-affinity setting see this post by William Lam. If you are configuring vCenter HA on a version of vCenter prior to 6.7 Update 1 then see this post.