Patent ID: 8219747

Claim:
A storage system, comprising: a host computer; and a disk control device connected to the host computer for communications therewith, and configured to perform control over a disk device that stores therein data requested for writing from the host computer, wherein the disk control device includes: a host interface section connected to the host computer; a disk interface section connected to the disk device; a memory section that includes a memory area for temporary storage of data for communications with the host computer, and a memory section including an area for storage of control data of the storage system; and a processor section that includes a processor in charge of computing processing, and an area for storage of a program to be run by the processor, and in the storage system, for data transmission from the host interface section or the disk interface section to the memory section, when the data requested by a transmission source for storage is successfully stored in a transmission destination, the transmission destination is put in a first mode for communications of returning a response back to the transmission source, wherein for data transmission from the processor section to the memory area of the memory section, the transmission source assigns a next source-side serial number to the data to be stored in the transmission destination, and when destination-side comparison determines the next source-side serial number assigned to the data is not the same as a next destination-side serial number under management of the transmission destination, the transmission destination is put in a second mode for communications of forwarding an error response back to the transmission source, and responsive to the error response, the transmission source resets to a reset source-side serial number and transmits a command with the source-side serial number to the transmission destination, for the transmission destination to reset to a reset destination-side serial number which matches the reset source-side serial number, and then the transmission source transmits a confirmation command which is assigned an incremented source-side serial number, to the transmission destination, for confirming that an incremented destination-side serial number of the transmission destination is the same as the incremented source-side serial number assigned to the confirmation command, and if the incremented destination-side serial number is not the same as the incremented source-side serial number assigned to the confirmation command, the transmission destination returns an abnormal response packet back to the transmission source.