US Patent 7606970 Hybrid disk drive and method of controlling data therein

A hybrid disk drive is utilized to achieve speed optimization and minimization of power consumption by installing a flash memory device in the hybrid disk drive and efficiently controlling data flow between the flash memory device and the disk drive. The hybrid disk drive includes a volatile memory unit, a nonvolatile memory unit, a disk unit, a host interface and a buffer controller disposed between the volatile memory unit, the nonvolatile memory unit, the host interface and the disk unit. The disk unit stores data by magnetizing the surface of the disk. The host interface receives a read data command from the host and transmits the data stored in the volatile memory unit to the host. The buffer controller is configured to read the data from the nonvolatile memory unit if the data is not stored in the volatile memory unit when the read data command is received from the host interface. The buffer controller also controls the storing of the read data in the volatile memory unit if the data is stored in the nonvolatile memory unit. Alternatively, if the data is not stored in the nonvolatile memory unit, the controller reads the data from the disk unit and stories it in the volatile memory unit.