According to one embodiment, a disk storage apparatus includes a write module, an operation module, and a controller. The write module is configured to write data, in units of blocks, in a designated write area of a disk. The operation module is configured to perform an exclusive OR operation on the blocks of data. The controller is configured to control the write module, causing the write module to write, in a designated block, recovery data that is a result of the exclusive OR operation on all data blocks written in the designated write area.