Patent ID: 8108597

Claim:
A computer system comprising: a plurality of tape media for storing data; a first storage device configured to perform random access that is an access with randomly different access destinations at a rate higher than the tape media; a virtual storage device that emulates said first storage device; a second controller for controlling access to said plurality of tape media and said first storage device; a second storage device for storing data; a third storage device having said virtual storage device mapped therewith; and a first controller for controlling data access to said second storage device or said third storage device, said first controller including an internal memory stored with a disk control program for performing storage device pair copying and deleting and a pair management table for recording storage device pairing copying and deleting as preformed, wherein said first controller receives a Copy Indication, checks if said virtual storage device is active, if said virtual storage device is active then performs data copying from said third storage device to said second storage device in response to said Copy Indication and, at this time, sends a Data Access Command indicating said virtual storage device for data access generated in said third storage device, and displays a pair duplex status of said third storage device and said second storage device, said second controller reserves a storage space on said first storage device, reads data from an object tape medium, which is a tape medium corresponding to said virtual storage device, of said plurality of tape media, to said storage space, and when a Data Access Command relating to said virtual storage device is received, performs data access to said storage space, rather than to said object tape medium, and after said first controller receives the Delete Indication, even if there is an update in said third storage device, said first controller does not manage a difference between said third storage device and said second storage device that originated due to said update and then, when said Copy Indication is received, sends said Write Command for writing all the data located in the third storage device after the update to said second storage device, and displays a pair simplex status of said third storage device and said second storage device.