Patent ID: 7058753

Claim:
A data access system having a storage system and a host device that is connected to said storage system with allowed for communication thereto: wherein said storage system comprises physical or logical plural data storage areas including an online storage area that is in an online state to said host device; and an access control means enabling said host device to access a target storage area, which is a data storage area other than said online storage area and is a target that said host device wants to access, through said desired or predetermined online storage area, wherein said access control means comprises a host communication means as a communication interface to said host device, a storage area communication means for accessing said plural data storage areas, and a cache memory for transferring the read data that is read from said data storage area or the write data that is received from said host device between said host communication means and said storage area communication means; said cache memory secures a cache slot, which is a storage area for temporarily storing said read data or said write data, therein; said cache slot is provided with dedicated to one data storage area; and upon receiving the access request to said desired online storage area from said host device, said host communication means secures a cache slot for target that is dedicated not to said desired online storage area but to a target storage area that is designated by the target information that is carried by said received access request on said cache memory; and thereby, the read data that is read from said target storage area or the write data to be written in said target storage area is temporarily stored in said secured cache slot for target.