There are few ways to achieve HA of a Virtual machine. The minimum prerequisite are 2 physical server with ESXi 5.x /6.x version and a vCenter server 5.x/ 6.x newer version, a shared Storage with vSAN /FC/ISCSI/NFS choose the SAN box based on the application IOPS required for a good performance.
Refer the Hardware compatible list to check the supported hardware and software for vSphere Environment. https://www.vmware.com/resources/compatibility/search.php
Types of failover available:
VSphere HA: VMware HA provides high availability for virtual machines by pooling them and the hosts they reside on into a cluster. Hosts in the cluster are monitored and in the event of a failure, the virtual machines on a failed host are restarted on alternate hosts.
Failover Clustering and Microsoft Cluster Service: VMware vSphere supports clustering using MSCS across virtual machines. Clustering virtual machines can reduce the hardware costs of traditional high-availability clusters.