What is the difference between vMotion, High Availability and Fault Tolerance?
Which of the above features provides automatic failover?
Do I need a shared storage for automatic failover?
What is the limitation of vSphere Storage Appliance?
vMotion - vMoiton allows you to move a running virtual machine from physical ESXi host to another without any downtime. The VMotion event is initiated by the administrtor or can be done automatically with VMware DRS - this requires shared storage
VMware HA - provides for failover in the event of an ESXi host failure. The VMs running on the ESXi host that fails will restart on other hosts in the HA clustrer. This can also be configured to monitor individual VMs. This requires share storage - this will provide automatic failover
VMware FT - provides a seemless failover in the event of a VM or host failure - in short FT you have your primary VM and a shadow VM mirroring what the primary VM is doing - the VMs are running on different ESXi hosts - in the event of a failure of the primary VM the shadow VM will come online and take on the load - this will have no downtime - this will provide automatic failover
Virtal Storage Applicance - I would say the biggest limitation is the VSA only supports a maximum of 3 hosts - the VSA can be used to provide shared storage to support vMotion and HA