Patent ID: 8069272

Claim:
A storage system comprising: a plurality of clusters; wherein each cluster includes access control unit which controls intracluster transfer of data within each cluster and intercluster transfer of data between the clusters; wherein the access control unit determines whether the data transfer is the intracluster transfer or the intercluster transfer; wherein the access control unit determines whether the intracluster transfer satisfies a first transfer restriction condition when the data transfer is the intracluster transfer; wherein the access control unit determines whether the intercluster transfer satisfies a second transfer restriction condition when the data transfer is the intercluster transfer, the second transfer restriction condition is equal or stricter than the first transfer restriction condition and includes information which indicates that a transfer command type of the data transfer satisfies a read only mode; and wherein the access control unit executes the data transfer when the intracluster transfer satisfies the first transfer restriction condition or when the intercluster transfer satisfies the second transfer restriction condition.