Storage system, apparatus, and method for failure recovery during unsuccessful rebuild process

A storage control apparatus that controls recording of data in a plurality of storage devices such that the data recorded in the plurality of storage devices is made redundant between different storage devices, the storage control apparatus comprising one or more processors configured to perform a procedure including:

• executing access processing to access the data recorded in the plurality of storage devices in response to an access request from a host apparatus;
• continuing the access processing, when a first storage device is in failure in the access processing, using remaining ones of the plurality of storage devices except the first storage device;
• executing, upon failure of the first storage device, a rebuild process in a spare storage device to store the same data as data recorded in the first storage device;
• writing data in the spare storage device, as part of the access processing, in response to each write request received from the host apparatus during the rebuild process;
• determining, when the rebuild process fails to read data once from an address in a second storage device, whether the writing in the spare storage device has been performed at an address corresponding to the address of the failed reading;
• considering the rebuild process as having been completed for the data that the rebuild process has failed to read once, when the determining finds that the writing in the spare storage device has been performed at the address corresponding to the address of the failed reading;
• and
• reading data out from the first storage device at an address corresponding to the address of the failed reading, when the determining finds that the writing in the spare storage device has not been performed at the address corresponding to the address of the failed reading.

A storage control method for a storage control apparatus that controls recording of data in a plurality of storage devices such that the data recorded in the plurality of storage devices is made redundant between different storage devices, the storage control method comprising:

• executing access processing to access the data recorded in the plurality of storage devices in response to an access request from a host apparatus;
• continuing the access processing, when a first storage device is in failure in the access processing, using remaining ones of the plurality of storage devices except the first storage device;
• executing, upon failure of a first storage device in the plurality of storage devices, a rebuild process in a spare storage device to store the same data as data recorded in the first storage device;
• writing data in the spare storage device, as part of the access processing, in response to each write request received from the host apparatus during the rebuild process;
• determining, when the rebuild process fails to read data once from an address in a second storage device, whether the writing in the spare storage device has been performed at an address corresponding to the address of the failed reading;
• considering the rebuild process as having been completed for the data that the rebuild process has failed to read once, when the determining finds that the writing in the spare storage device has been performed at the address corresponding to the address of the failed reading;
• and
• reading data out from the first storage device at an address corresponding to the address of the failed reading, when the determining finds that the writing in the spare storage device has not been performed at the address corresponding to the address of the failed reading.