A cache and disk management method is provided. In the cache and disk management method, a command to delete all valid data stored in a cache, or specific data corresponding to a part of the valid data may be transmitted to a plurality of member disks. That is, all of the valid data or the specific data may exist in the cache only, and may be deleted from the plurality of member disks. Accordingly, the plurality of member disks may secure more space, an internal copy overhead may be reduced, and more particularly, solid state disks may achieve better performance.