Computer system and control method thereof

A computer system having a plurality of physical devices, comprising:

• a volatile memory serving as a data storage part comprising a plurality of cells to store data, wherein the plurality of cells of the volatile memory are assigned to the plurality of physical devices by associating addresses of the plurality of cells with the plurality of physical devices, respectively;
• a non-volatile memory to store information associating the addresses of the plurality of cells of the volatile memory with the plurality of physical devices, respectively;
• and
• a controller to inspect and determine whether there is a defective cell in the data storage part if a condition to execute a cell inspection function is met, and, if a defective cell is found, to set the defective cell to be assigned to a predetermined virtual device different from each of the plurality of physical devices to prevent access to the defective cell from the plurality of physical devices,
• wherein the defective cell is assigned to the predetermined virtual device by updating the information stored in the non-volatile memory such that the address of the defective cell of the volatile memory is associated with the predetermined virtual device.