Patent ID: 8225136

Claim:
A control method for controlling a controller connected to a plurality of storage units storing data, the controller including a cache and a buffer, the method comprising: storing data in the cache; generating parity data corresponding to the data stored in the cache and storing the parity data in the buffer; writing the data stored in the cache and the parity data stored in the buffer into the plurality of the storage units; reading the data and the parity data from the plurality of storage units; checking error over the read out data by using the read out parity data; storing, if an error is detected in the read out data and the read out parity data, data for reading a plurality of data constituting a stripe in each of the plurality of storage units in the buffer, regenerating parity data by using the plurality of data readout from the storage units; and overwriting the plurality of data and the parity data into the plurality of the storage units.