Patent ID: 7380058
Filing Date: 2008-05-27
Classification: G06F

Abstract:
1. A method for writing data to a cache memory wherein a data write-in request is issued from an information processor to a storage control apparatus, the storage control apparatus including a plurality of channel control units each having an interface with the information processor; a disk control unit having an interface with a storage device for storing data; a local cache memory disposed in each channel control unit for temporarily storing data to be interchanged between the information processor and the storage device; a dedicated data transfer path between at least two of the local cache memories; a connector unit to provide data paths among the plurality of channel control units and the disk control unit separate from the dedicated data transfer path; a global cache memory connected to the connector unit; and a disk drive connected to the global cache memory, the method comprising: receiving data to be written from the information processor; writing the data to be written to a first local cache memory of a first channel control unit, wherein if the first local cache memory does not have sufficient capacity to store the data to be written then first transmitting an amount of data stored in the first local cache memory to the global cache memory by way of the connector unit in order to obtain sufficient capacity in the local cache memory to store the data to be written; transmitting the data to be written through the dedicated data transfer path to a second channel control unit connected to the first channel control unit; writing the transmitted data to a second local cache memory of the second channel control unit; receiving through the dedicated data transfer path an acknowledgement indicating that writing of the transmitted data to the second local cache memory disposed in the second channel control unit has completed; transmitting the acknowledgement to the information processor to notify the information processor that data written to the second local cache memory of the second channel control unit has completed; writing data in the first local cache memory and the second local cache memory which is not yet reflected to the global cache memory out to the global cache memory to reflect the data into the global cache memory; removing power from the first channel control unit and the second channel control units after the data is reflected into the global cache memory; writing data in the global cache memory which is not yet reflected to the disk drive out to the disk drive to reflect the data into the disk drive; and removing power from the global cache memory, the disk control unit, and the disk drive after the data is reflected to the disk drive.