vSphere Fault Tolerance on the ESXi host platform provides continuous availability by protecting the primary virtual machine virtual machine with a secondary virtual machine that runs simultaneously on a separate host. Inputs and events performed on the primary virtual machine are recorded and replayed on the secondary virtual machine, which ensures that the two remain in an identical state. For example, mouse-clicks and keystrokes are recorded on the primary virtual machine and replayed on the secondary virtual machine. Because the secondary virtual machine is running simultaneously with the primary virtual machine, it can take over at any point without service interruption or loss of data.