Systems and methods for migration between computing machines are disclosed. The source and target machines can be either physical or virtual; the source can also be a machine image. The target machine is connected to a snapshot or image of the source machine file system, and a redo-log file is created on the file system associated with the target machine. The target machine begins operation by reading data directly from the snapshot or image of the source machine file system. Thereafter, all writes are made to the redo-log file, and subsequent reads are made from the redo-log file if it contains data for the requested sector or from the snapshot or image if it does not. The source machine continues to be able to run separately and simultaneously after the target machine begins operation.