Patent ID: 7765452

Claim:
A disk controller controlling reading and writing of data provided with check codes from or into a disk drive, comprising: a programmed processor to control the disk controller according to a process including: setting, by an external control, a check code conversion operation mode selected from a first mode, a second mode, or a third mode, or any combinations thereof, determining whether check codes added to data read from the disk drive are first type check codes or second type check codes, converting the first type check code into the second type check code upon determining the check code added to the read data being the first type check codes, and writing the data with the second type check code into the disk device, wherein the programmed processor performs as the first mode the determining, the converting, and the writing in background at a time different from processing read/write requests from a host device, as the second mode the determining, the converting and the writing during a disk patrol operation to check the disk drive at regular intervals, and for a certain quantity of data for each disk patrol operation, and as the third mode performs the determining, the converting and the writing when data is read from the disk drive in response to a data read request from a host device.