Storage device and rebuild process method for storage device

A storage device comprising:

• a storage unit including a plurality of memory devices each having a write cache;
• a first control unit that redundantly stores data in the plurality of memory devices;
• a second control unit that performs a rebuild process of rebuilding the data;
• a write cache control unit that, at a time of of the rebuild process, enables a write cache of a memory device that stores rebuilt data;
• and
• a progress management unit that is configured using a nonvolatile memory and manages, as progress information of the rebuild process, an address of rebuilt data for which rebuilding is completed and which is written in the write cache,
• wherein, in a case where power discontinuity is caused during the rebuild process and then power is restored, the second control unit calculates an address that is before an address of last written rebuilt data by an amount corresponding to a capacity of the write cache based on the progress information of the rebuild process managed by the progress management unit and resumes the rebuild process from that calculated address.