A data saving device, system, and method rapidly and deterministically saves data of a computer system. The device may mark data that must be saved when the computer is shut down. In certain embodiments, a boot control module detects a condition requiring a rapid deterministic data saving operation, such as a power failure and reboots the computer, deterministically terminating all existing processes. Additionally, the boot control module loads a data transfer kernel in place of a standard operating kernel used for normal operation. The data transfer kernel supports a set of processes exclusively dedicated to saving data. The data transfer kernel configures the computer and storage devices for the data transfer and saves the marked data with a minimum of interruptions from other processes. Also, the data transfer kernel may shut down the computer and the storage devices after transferring data.