The technique disclosed in JP-2009-538482-T, which makes restructuring of the data essential when the memory device is added, has a problem in that taking a long time for distribution of the data may inhibit prompt decrease in the consumption rate for the remaining life.

It is desirable to provide a storage device and a storage management method by which the distribution of the data to the added memory device may be carried out in a short period of time.

A storage device according to one aspect of the present disclosure is a storage device which includes a control unit and a plurality of memory devices, in which a parity group is configured by including a first number of pieces of user data and redundant data generated from the first number of pieces of the user data, in which the user data and the redundant data in the parity group are stored in the different memory devices from each other, and in which, in a case where any new memory device is added to the storage device, the control unit carries out first data distribution processing moving any piece of the user data in the parity group from the existing memory devices to the added memory device and second data distribution processing increasing the number of pieces of the user data configuring the parity group from the first number to a second number after the first data distribution processing, and storing the resultant user data in the plurality of memory devices.

According to the present invention, distribution of data to the added memory device may be carried out in a short period of time.