Channel adapter and disk array device

A method of controlling a channel adapter that is used in a disk array device and controls data exchange with an upper-level device, the method comprising the steps of:

• in a case where partial data of data already transmitted to the upper-level device is to be retransmitted to the upper-level device:
• reading the partial data from an internal memory and transmitting the partial data to the upper-level device;
• comparing an output guarantee code computed in regard to all data with an input guarantee code computed when the data is inputted to the internal memory;
• and
• determining that transmission of the partial data has been conducted normally in a case where both guarantee codes match.

A method of controlling a channel adapter that is used in a disk array device and controls data exchange with an upper-level device, the method comprising:

• a first step of storing data from an external memory in an internal memory;
• a second step of computing and retaining an input guarantee code in regard to all data when the data is inputted to the internal memory;
• a third step of reading the data from the internal memory;
• a fourth step of computing and retaining an output guarantee code in regard to all of the read data;
• a fifth step of transmitting the read data to the upper-level device;
• a sixth step of determining, and notifying the upper-level device, whether or not transmission has been conducted normally by comparing the input guarantee code and the output guarantee code;
• a seventh step of determining whether or not there is a retransmit request from the upper-level device in regard to partial data of the data sent to the upper-level device;
• an eighth step of reading the partial data from the internal memory and transmitting the partial data to the upper-level device in a case where there is a request to retransmit the partial data;
• a ninth step of rereading the data stored in the internal memory;
• a tenth step of again computing an output guarantee code in regard to all of the reread data;
• and
• an eleventh step of determining7 and notifying the upper-level device, whether or not transmission has been conducted normally by comparing the again-computed output guarantee code and the input guarantee code computed in the second step.

A disk array device comprising:

• a channel adapter that is connected to an upper-level device via a communications network and controls data exchange with the upper-level device;
• a storage device that stores data;
• a disk adapter that controls data exchange with the storage device;
• and
• a cache memory that stores data read from the storage device or data received from the upper-level device,
• wherein the channel adapter includes:
• an internal memory that stores data from the cache memory,
• an input guarantee code computing unit that computes and retains an input guarantee code in regard to the data stored in the internal memory in a case where the data is stored in the internal memory,
• an output guarantee code computing unit that computes and retains an output guarantee code in regard to the data read from the internal memory in a case where the data is read from the internal memory,
• a communication unit that transmits the data read from the internal memory to the upper-level device, and
• a control unit which, in a case where partial data of the data read from the internal memory is to be retransmitted to the upper-level device, (1) uses the communication unit to transmit partial data to the upper-level device, (2) uses the output guarantee code computing unit to compute the output guarantee code in regard to the data read from the internal memory, and (3) compares the computed output guarantee code with the input guarantee code and determines that transmission of the data read from the internal memory has been conducted normally in a case where both guarantee codes match.