Patent ID: 6671767
Filing Date: 2003-12-30
Classification: G06F

Abstract:
The storage subsystem comprising:plural storage units; and a storage control unit that is connected to a central processing unit and has an internal cache memory for temporarily storing data exchanged between said central processing unit and said storage units, wherein said storage subsystem is connected to said central processing unit by an I/O interface protocol by which said central processing unit issues I/O requests including a chain of plural commands and data to said storage control unit asynchronously with responses from said storage control unit, wherein said storage control unit has means that decides an order of processing said plural commands and data from said central processing unit independently of the order they were received, and executes said commands, and wherein said plural storage units are under control of said storage control unit, wherein said storage control unit has means that, in the case where a RAID configuration is taken to distribute data of one logical volume across said plural storage units, mercies plural commands received from said central processing unit into one command group, when processing target data of plural commands of said command group does not exist on said cache memory, in parallel activates more than once reading of processing target data of commands of said command group into said cache memory from the individual storage units in which said processing target data of said commands is stored, and in order of completion of said reading, for said commands of said command group, performs data transfer with said central processing unit in Parallel with said reading, and wherein said storage control unit has means that merges plural commands received from said central processing unit into one command group, when processing target data of plural commands of said command group does not exist on said cache memory, in parallel activates more than once said reading of the processing target data into said cache memory from said storage units in which said respective processing target data of said commands is stored, according to operation ratio of each of said storage units; and in order of completion of said reading, performs data transfer with said central processing unit in parallel with said another reading.