STORAGE SYSTEM, STORAGE APPARATUS, AND OPTIMIZATION METHOD OF STORAGE AREAS OF STORAGE SYSTEM

摘要

This invention is intended for the purpose of providing the storage system, the storage apparatus, and the storage system by which, even if the storage areas allocated to the virtual volume are managed in management units set by the RAID group, overhead for parity calculation does not become excessive. This invention, by releasing a specific management unit not fully utilized for page allocation from allocation to the virtual volume and migrating the allocated pages belonging to this specific management unit to the other management unit, makes the storage areas of the specific management unit available for the write accesses for the other virtual volumes from the host computer.