An arithmetic operation unit receives a request to update a first data group during restoration using first history information and generates second history information indicating a history of updates. The arithmetic operation unit predicts a time taken until completion of restoration using the second history information on the basis of an amount of the second history information. The arithmetic operation unit compares the predicted time with a threshold and limits at least part of updates of the first data group during the restoration using the second history information on the basis of the comparison result.