an installation unit separately setting a system area and a meta buffer area on the computer hard disk and reserving areas for a meta information table, a system area information table, and a mapping table in the meta buffer area;

an initialization/recovery unit initializing the system area information table, in which each of clusters in the system area is marked as one among “original”, “protected”, and “non-protected” based on one of a volume bitmap and a file allocation table (FAT), and initializing the mapping table storing mapping relation between a cluster position recognized by a file system and a cluster position where data is actually stored in the system area;

a write operation processing unit, with respect to a write operation on a cluster of the system area designated by the file system, performing the write operation on another corresponding cluster designated by the mapping table when the cluster designated by the file system is marked as “original” in the system area information table, performing the write operation on a cluster corresponding to an empty space in the system area when the cluster designated by the file system is marked as “original” in the system area information table and a value designated by the mapping table with respect to the cluster designated by the file system indicates an initial state, storing data read from the cluster designated by the file system in an empty space in the system area and performing the write operation on the cluster designated by the file system when the cluster designated by the file system is marked as “protected” in the system area information table, and performing the write operation on the cluster designated by the file system in otherwise cases;

a read operation processing unit, with respect to a read operation on a cluster of the system area designated by the file system, performing the read operation on another corresponding cluster designated by the mapping table, and performing the read operation on the cluster designated by the file system only when a corresponding value designated by the mapping table indicates the initial state;

a current state backup unit sequentially reading all items of the mapping table one by one, storing data stored in a cluster designated by the mapping table in a cluster designated by the file system with respect to an item in which the cluster designated by the file system is different from the cluster designated by the mapping table, and then calling the initialization/recovery unit to perform initialization; and

a removing unit removing the meta buffer area set by the installation unit to integrate the meta buffer area into the system area,

wherein when the cluster designated by the file system is marked as “original” in the system area information table and when a corresponding value designated by the mapping table is set to the initial state, the write operation processing unit comprises securing an empty space in the system area, performing the write operation on a cluster allocated to the secured empty space, and marking the cluster allocated to the secured empty space as “protected” in the system area information table, and

when the cluster designated by the file system is marked as “protected” in the system area information table, the write operation processing unit comprises securing an empty space in the system area, reading data from the cluster designated by the file system requesting the write operation, storing the read data in the empty space, performing the write operation on the cluster designated by the file system, changing a protection state of the empty space where the read data has been stored into “protection” in the system area information table.