Patent ID: 7660946

Claim:
A storage control system for performing data processing according to a request from a host system, comprising: a first storage controller; and a second storage controller connected to said first storage controller and having a first logical volume and a second logical volume, wherein said first storage controller comprises: a virtual volume associated with said first logical volume of said second storage controller; and a cache memory associated with said virtual volume, wherein, in accordance with a purge command, said first storage controller purges a storage area in said cache memory, wherein, in accordance with a restore command, said second storage controller reads data to be restored from said second logical volume, stores the data in said first logical volume, thereby forming a copy pair of said first logical volume and said second logical volume, and sends the data to said first storage controller, wherein said first storage controller receives the data from said second storage controller and stores the data in said storage area of said cache memory, wherein said first storage controller determines whether data of a storage area of the cache memory corresponding to the virtual volume to be accessed by the host reflects restored data, and when the data of the cache memory storage area corresponding to the virtual volume does not reflect the restored data, the first storage controller purges the data of the cache memory storage area corresponding to the virtual volume and subsequently stores the restored data in the said cache memory storage area corresponding to the virtual volume, wherein when the host issues an I/O to the virtual volume, the first storage controller acquires the cache area associated with the I/O request, and determines whether control data of the cache area is NULL, wherein when the control data of the cache area is not NULL, the first storage controller compares a generation number of the received I/O request with an overall generation number, wherein when the generation number coincides with the overall generation number, the first storage controller uploads the restored data to the storage area of the cache memory corresponding to the virtual volume, and wherein when the generation number does not coincide with the overall generation number, the first storage controller determines that the data of the cache memory storage area corresponding to the virtual volume is data that does not correspond to the restored data, and the first storage controller purges the data of the cache memory storage area corresponding to the virtual volume, and subsequently stores the restored data.