File control system and file control device

A file control system, performing DMA transfer and comprising a plurality of file control devices, each of which is provided between a host computer and an external storage device, and its controlling of writing and reading of data to the external storage device is based on commands from the host computer,

• wherein a first file control device among the plurality of the file control devices comprises:
• a first memory, which store data of the external storage device and a first error detection code given in advance to the data;
• a first consistency determination unit for checking the consistency between the data obtained from the first memory and the first error detection code given in advance to the data;
• a error detection code changing unit, after performing the checking of the first consistency determination unit, for changing the error detection code added to the obtained data from the first error detection code to a second error detection code;
• a data changing unit, when the inconsistency is detected by the first consistency determination unit, changing at least a part of the data of the processing result of the error detection code changing unit;
• a DMA transfer execution unit for executing DMA-transfer of the data of the processing result of the error detection code changing unit to a second file control device among the plurality of the file control devices,
• and the second file control device comprises:
• a second memory capable of storing the data received from the first file control device;
• a second consistency determination unit for checking the consistency between the second error detection code and the data associated to the second error detection code, which are included in the data received from the first file control device;
• a data processing unit for discarding data received from the first file control device when the inconsistency is detected by the second consistency determination unit, and for storing the received data in the second memory when the inconsistency is not detected by the second consistency determination unit.