According to an aspect of an embodiment, a storage system for storing data from a host device, comprising: a plurality of storage units for storing data, in a manner to enable recovery of data stored in one of said storage units by the use of data stored in the rest of storage units; an extra storage unit; and a controller for controlling said storage units and said extra storage unit according to a process comprising: receiving information indicative of fault prediction in one of storage units, recovering data stored in said one of said storage units by the use of data storage in the rest of said storage units, and writing the recovered data into said extra storage unit.