Patent ID: 7689837

Claim:
A computer system comprising: a first storage system coupled to a computer; a second storage system coupled to the first storage system; and a management computer coupled to the first storage system and the second storage system, wherein the first storage system comprises: a plurality of first volumes that stores data accessed by the computer; a first control unit which controls the plurality of first volumes based on access from the computer; and a first data encryption module which encrypts or decrypts data stored on one of the plurality of first volumes based on a first encryption method; wherein the second storage system comprises: a plurality of second volumes that stores data accessed by the computer; a second control unit which controls the plurality of second volumes based on access from the computer; and a second data encryption module which encrypts or decrypts data stored on one of the plurality of second volumes based on a second encryption method, wherein the management computer comprises a memory that stores encryption method compatibility information which indicates compatibility between a plurality of encryption methods including the first encryption method and the second encryption method, wherein when the management computer receives a migration instruction of data migration of encrypted data stored in one of the plurality of first volumes, the management computer searches the encryption method compatibility information for an encryption method which has compatibility with the first encryption method used in the first data encryption module included in the first storage system, and wherein when the second encryption method which is used in the second data encryption module included in the second storage system is compatible with the first encryption method, the management computer selects the second storage system as a destination of the data migration, and instructs to migrate the encrypted data stored in the one of the plurality of first volumes, for which the migration instruction was received, to one of the plurality of second volumes.