Patent attributes
A storage apparatus, including a first group including first storage media storing data and a second group including second storage media storing no data, makes an area of the first storage media which stores updating target data an invalid area and to store updated data into an area of the first storage media, migrates to the second storage media data stored in an area other than the invalid areas of the set of the first storage media when determining that the first group includes the set of the first storage media in which the sum of the invalid areas is not less than the capacity of the one storage medium, and moves a group including the first storage media from which migration of the data is completed from the first group to the second group.
