The main service running on the vCenter Server is known as vpxd or VMware Virtual Server service. When an ESXi host is added to the vCenter Server, there is an agent service called vpxa, which is installed and started on the ESXi host. Vpxa acts as an intermediary service between the vpxd service running on the vCenter Server and hostd service running on the ESXi host. The hostd service running on the ESXi host is mainly responsible for managing most of the operations on the host.

It knows all the registered virtual machines, their status, and the storage volumes that are visible to the host. When commands such as creating, migrating, or suspending a virtual machine from vCenter Server is issued, the vpxd service running on the vCenter Server sends the command to vpxa, and vpxa in turn forwards it to hostd, which then executes the command.

If a command is issued through the vCenter Server, the vCenter Server database is also updated. vCenter...