1. A database (DB) system comprising: a processor; a memory configured to store DB data; a cache storage device configured to store a restore file of the DB data; and a disk storage device having a disk storage, and configured to store the restore file of the DB data on the disk storage, wherein the cache storage device is faster than the disk storage device in access speed, wherein the processor is configured to store the restore file of the DB data to the disk storage device directly or using the cache storage device, and wherein the processor is configured to determine, according to a state of the DB system, whether to activate the cache storage device to store the restore file of the DB data to the disk storage device.