When you deploy vCenter Server, you must build a highly available architecture that can handle workloads of all sizes.
Availability is critical for solutions requiring continuous connectivity to vCenter Server. To avoid extended periods of downtime, users should run vCenter Server in highly available configurations.
Two options can help you achieve continuous connectivity:
Option 1: Using a vSphere High Availability cluster and Watchdog
Option 2: Using a Microsoft Cluster Service (MSCS) cluster
Use option 1 when your vCenter Server environment is virtualized. Use option 2 when vCenter Server is installed on Windows.
In this document, references to MSCS also apply to WSFC on corresponding Windows Server versions.