FT is a new feature which VMware introduced to the world during VMworld 2008. The feature is a continuous availability solution for use with some virtual machines. The following notes were compiled from session BC2621 at VMworld which introduced the forthcoming FT feature from VMware’s Application vServices. The feature should be available sometime in 2009.
FT will enable a VM to be protected with zero downtime and zero data loss due to a hardware failure. FT allows for a VM to have a secondary copy running simultaneously on a second ESX host which is executing every instruction and every input in lockstep with the primary VM. In the event of a failure, the secondary VM becomes the primary within a matter of seconds, while preserving state and without disconnecting any connections to the virtual machine. All traffic is redirected to the secondary. In addition, once the secondary assumes the role as primary, it spawns a new secondary instance on another ESX host and brings full fault tolerance back to the virtual server.