One of the failover options ESX/ESXi provides is VMware High Availability (HA).

VMware HA allows you to organize virtual machines into failover groups. When a host fails, all its virtual machines are immediately started on different hosts. When a virtual machine is restored on a different host, it loses its memory state, but its disk state is exactly as it was when the host failed (crash-consistent failover). Shared storage (such as a SAN) is required for HA.

Note

You must be licensed to use VMware HA.