Patent ID: 7831767
Filing Date: 2010-11-09
Classification: G06F

Abstract:
1. A port selector for a storage system, which storage system includes: a memory unit including a plurality of storage devices; a plurality of control units for performing processing for data I/O to/from the memory unit in response to a data I/O request from a host device, each control unit comprising: memory for storing a control program; a controller for controlling data I/O processing and generating a command in response to the data I/O request according to the control program; and an initiator for carrying out a first conversion of the command corresponding to a protocol, adding cyclic redundancy check (CRC) to the command, and controlling, according to the command, access to a storage device that is the target of the data I/O request in the memory unit; a plurality of connection paths connecting each of the control units to each of said plurality of storage devices included in the memory unit; and the port selector placed on any of the connection paths for controlling data I/O and for carrying out a second conversion of the command, wherein the port selector corresponds to one of the plurality of storage devices, wherein each controller is configured to predict data that forms the command after being subjected to the first conversion and the second conversion, to calculate a first checksum for the predicted data, and to add the first checksum to the command before the first conversion and the second conversion of the command, wherein the port selector is configured to judge whether or not any command error has occurred in at least one command of a first controller, which at least one command has been subjected to the first conversion and the second conversion, based on comparison between the first checksum and a second checksum, which second checksum is calculated from the data that forms the at least one command subjected to the first conversion and the second conversion, and to perform processing in response to the judgment for the first controller, and wherein the value of the first checksum does not change during a period from after a time it is added to the command until after the at least one command is received by a targeted storage device included in the plurality of storage devices.