File control system and file control device

A file control device, used in a file control system performing direct memory access transfer and including a plurality of file control devices, each of the file control device being provided between a host computer and an external storage device and controlling writing and reading of data to the external storage device based on commands from the host computer, the file control device comprising:

• a memory to store data of the external storage device and a first error detection code provided to the data in advance, and data received from a first different one of the plurality of file control devices;
• a first consistency determination unit to check consistency between data obtained from the memory and the first error detection code;
• an error detection code changing unit to change, after performing the checking of the first consistency determination unit, an error detection code added to the obtained data from the first error detection code to a second error detection code;
• a data changing unit to change, when an inconsistency is detected by the first consistency determination unit, at least a part of the data of the processing result of the error detection code changing unit;
• a direct memory access transfer execution unit to execute direct memory access transfer of the data of the processing result of the error detection code changing unit to the first different one or a second different one of the plurality of the file control devices;
• a second consistency determination unit to check the consistency between a third error detection code and data associated with the third error detection code, which are included in the data received from the first different one of the plurality of file control devices;
• and
• a data processing unit to discard data received from the first different one of the plurality of file control devices when an inconsistency is detected by the second consistency determination unit, and to store the received data in the memory when the inconsistency is not detected by the second consistency determination unit.

A file control system performing direct memory access transfer, the file control system comprising:

• a first file control device and a second file control device, the first file control device including:
• a first memory to store data received from an external storage device and a first error detection code, the received data being associated with a second error detection code;
• a first determination unit to obtain the second error detection code, and to check for errors within the stored data based on a comparison of the first error detection code and the second error detection code;
• an error detection code unit to replace the first error detection code associated with the received data with a third error detection code;
• a data changing unit to change at least a part of the received data when an error is detected;
• a direct memory access transfer execution unit to execute direct memory access transfer of a result of the error detection code unit and the data changing unit to the second file control device as first device data;
• the second file control device including:
• a second memory to store the first device data;
• a second determination unit to check for errors within the first device data based on the first device data and the third error detection code associated with the first device data;
• and
• a data processing unit to discard the first device data if an error is detected and to store the first device data in the second memory if the error is not detected by the second consistency determination unit.