Proposed are a management apparatus and a management method capable of improving the stability of the overall computer system. In a computer system which manages a storage area provided by each of a plurality of mutually connected storage apparatuses as a logical pool, provides to a host computer a virtual volume associated with the logical pool, and assigns a real storage area from the logical pool to the virtual volume when the host computer writes into the virtual volume, when a storage apparatus is added to the plurality of storage apparatuses, the host computer is controlled to switch the access path to the added storage apparatus.