1. In a computer system, a method of providing fault tolerance in a virtual machine environment comprises: A) initiating execution of a primary virtual machine (VM) and a backup VM from the same state information; B) providing the backup VM with access to subsequent changes in the state information made by the primary VM while the primary VM and backup VM execute simultaneously; and C) reading the subsequent changes at the backup VM, such that the backup VM remains in a condition to provide fault tolerance for the primary VM.