A method of writing data includes receiving a record of a variable-length data format, creating a field-checking code for each field of the record received, creating a block-checking code in units of the fixed-length data for the data received, and writing data by reading the record, assembling fixed length data that includes the field-checking code and the block-checking code by using the field-checking code and the block-checking code, and transferring the data to a cache memory.