Patent ID: 8510515
Filing Date: 2013-08-13
Classification: G06F

Abstract:
1. A storage system comprising: a first storage apparatus, and a second storage apparatus, the first storage apparatus and second storage apparatus sharing an external volume, which is a logical volume provided by an external storage apparatus, wherein: the first storage apparatus comprises an external capacity pool, which is a storage area based on the external volume and is partitioned into multiple external pages that are sub-storage areas, and a first virtual volume, which is a virtual logical volume comprising multiple first virtual areas, and in a case of a write to a virtual area that has not been allocated a page, is configured to allocate an unallocated external page from the external capacity pool to the virtual area; the second storage apparatus comprises a second virtual volume, which is a virtual logical volume comprising multiple second virtual areas; and in a data migration from the first virtual volume to the second virtual volume, a data migration from a first virtual area to which an external page has been allocated to a second virtual area is completed in accordance with the following (a) and (b): wherein one of the first storage apparatus and the second storage apparatus;