Vmware HA
VMware High Availability deals primarily with ESX/ESXi host failure and what happens to the virtual machines (VMs) that are running on this host. HA can also monitor and restart a VM by checking whether the VMware Tools are still running. When an ESX/ESXi host fails for any reason, all the running VMs also fail. VMware HA ensures that the VMs from the failed host are capable of being restarted on other ESX/ESXi hosts.
Many people mistakenly confuse VMware HA with fault tolerance. VMware HA is not fault tolerant in that if a host fails, the VMs on it also fail. HA deals only with restarting those VMs on other ESX/ESXi hosts with enough resources. Fault tolerance, on the other hand, provides uninterruptible access to resources in the event of a host failure.
