In a computer system including a plurality of data storage apparatuses and a management computer, a given data storage apparatus, upon receipt of a control request for a local data storage apparatus from a management computer, accesses the hierarchical relation information between the storage areas in the local data storage apparatus and the storage areas of the other data storage apparatuses, and in the case where a storage area in the local data storage apparatus is set to correspond to a level lower than the other data storage apparatuses, transmits an approval request to the other data storage apparatuses. The given data storage apparatus, upon receipt of the approval from the other data storage apparatuses, executes the control request of the management computer.