Storage system comprising multiple storage apparatuses with both storage virtualization function and capacity virtualization function

A storage system comprising:

• a first storage apparatus;
• and
• a second storage apparatus, wherein:
• the first storage apparatus comprises a capacity pool that is partitioned into multiple pool pages and includes a storage area of an external logical volume provided by at least one storage apparatus,
• the second storage apparatus provides first virtual volume which is a virtual logical volume comprising multiple first virtual areas,
• in a case of receiving a write request from the computer to a virtual area in the first virtual volume to which a page is not allocated, an unallocated pool page of the external logical volume is allocated to the virtual area, and
• an authority to allocate the unallocated pool page of the external logical volume is assigned to the first storage apparatus.

A storage system comprising:

• a first storage apparatus;
• and
• a second storage apparatus, wherein:
• the first storage apparatus is configured to:
• provide a capacity pool that is partitioned into multiple pool pages and includes a storage area of an external logical volume provided by at least one storage apparatus;
• provide a first virtual volume which is a virtual logical volume comprising multiple first virtual areas, wherein in a case of receiving a write request from a computer to one of the first virtual areas in the first virtual volume to which a page is not allocated, an unallocated pool page of the external logical volume is allocated to one of the first virtual areas;
• migrate the first virtual volume to a second virtual volume provided by the second storage apparatus,
• if the second storage apparatus has an authority for allocating the unallocated pool page of the external logical volume, the second storage apparatus allocates the unallocated pool page of the external logical volume to a second virtual area to which a write request addressed, and
• if the second storage apparatus does not have the authority for allocating the unallocated pool page of the external logical volume, the second storage apparatus does not allocate the unallocated pool page to the second virtual area.

A storage control method comprising steps of:

• providing, by a first storage apparatus, a capacity pool that is partitioned into multiple pool pages and includes a storage area of an external logical volume provided by at least one storage apparatus;
• providing, by the first storage apparatus, a first virtual volume which is a virtual logical volume comprising multiple first virtual areas, wherein in a case of receiving a write request from a computer to one of the first virtual areas in the first virtual volume to which a page is not allocated, an unallocated pool page of the external logical volume is allocated to one of the first virtual areas;
• migrating, by the first storage apparatus, the first virtual volume to a second virtual volume provided by a second storage apparatus;
• allocating, by the second storage apparatus, the unallocated pool page of the external logical volume to a second virtual area to which a write request addressed;
• if the second storage apparatus has an authority for allocating the unallocated pool page of the external logical volume, allocating, by the second storage apparatus, the unallocated pool page of the external logical volume to the second virtual area to which the write request addressed;
• and
• if the second storage apparatus does not have the authority for allocating the unallocated pool page of the external logical volume, not allocating, by the second storage apparatus, the page to the second virtual area.