Storage system having a host that manages physical data locations of a storage device

A storage system comprising:

• a storage device including
• a controller and
• a nonvolatile semiconductor memory including a plurality of physical blocks, a physical block being a unit of data erasure;
• and
• a host including a processor configured to
• cause the controller to carry out reading of valid data stored in at least a physical block of the nonvolatile semiconductor memory, and
• cause the controller to carry out writing of the valid data in another physical block after one or more error bits included in the valid data are corrected through error correction.