Patent ID: 8713251

Claim:
A storage device comprising: a cache memory configured to store data from a host computer; a host adapter coupled to the host computer; a processor configured to control the cache memory; and a disk unit; wherein when the host adapter receives a first write request with write data from the host computer, the write data not being written in the cache memory, the host adapter is configured to: add positional information of the write data in the disk unit and check information set as first data to the write data; write the write data with the positional information and the check information to the cache memory; and check whether the positional information written in the cache memory is correct; and wherein when the host adapter receives a second write request with update data to the write data in the cache memory, the processor is configured to change the check information of the write data in the cache memory from the first data to second data; and then the host adapter is configured to: add positional information of the update data in the disk unit, which positional information is the same as the positional information of the write data and check information set as the first data to the update data; overwrite the write data with the positional information and the check information set as the second data in the cache memory by the update data with the positional information and the check information set as the first data to the cache memory; and check whether the positional information written in the cache memory is correct and whether the check information is set as the first data.