ERROR RECOVERING METHOD

PURPOSE:To recover errors with a retry function by providing a means which transmits error of a channel itself to a controller for input/ouput device and transmitting this error as error of a device lower than the channel from the controller to the channel. CONSTITUTION:An IO command from a CPU1 is sent to a channel CH2 to start a controller for input/output device (IOC) 3. If a channel error occurs in the channel CH2, a channel error status is given from the channel CH2 to the IOC3 through a transmission line 11. The IOC3 uses the same procedures as retry of errors of the IOC3 and lower devices to send a retry request to the channel CH2, and the channel CH2 starts retry to recover the error in the channel CH2.