In a computer system having a storage controller that receives a read request or a write request, a processor is configured to send to an interface device either a read-support indication, which is an indication to execute either all or a portion of read processing for read-data of the read request, or a write-support indication, which is an indication for either all or a portion of write processing for write-data of the write request. Then, the interface device, in accordance with either the read-support indication or the write-support indication, is configured to execute either all or a portion of the read processing for the read-data, or all or a portion of the write processing for the write-data, and to send to a host computer either a first response to the effect that the read processing has been completed, or a second response that the write processing has been completed.