A virtual machine management system is used to instantiate, wake, move, sleep, and destroy individual operating environments in a cloud or cluster. In various embodiments, there is a method and system for transferring an operating environment from a first host to a second host. The first host contains an active environment, with a disk and memory. The disk is snapshotted while the operating environment on the first host is still live, and the snapshot is transferred to the second host. After the initial snapshot is transferred, a differential update using rsync or a similar mechanism can be used to transfer just the changes from the snapshot from the first to the second host. In a further embodiment, the contents of the memory are also transferred. This memory can be transferred as a snapshot after pausing the active environment, or by synchronizing the memory spaces between the two hosts.