High Availability or HA is one of the primary reasons to migrate servers to a vi

High Availability or HA is one of the primary reasons to migrate servers to a virtual environment or to the Cloud. For this discussion address the following questions. 
Question #1. What are some of the virtualization-related services available to System Administrators to ensure high availability for important servers? Name and explain some of these features available in either Hyper-V or VMware and describe the benefits.
For example, Live Migration or vMotion, HA or Failover Cluster, DSR (Distributed Resource Scheduler), FT (fault tolerance), etc.
Question #2. Provide a real-world example of how some of these HA features are being used by real companies. I suggest searching for “case studies” or “use cases” of the tools that you choose to describe.
It is NOT enough to give a generic one-sentence definition of what is HA. You should do more research (and post more details) if you wish to learn about these very important features of virtualization.