Patent ID: 8862846

Claim:
A control apparatus for controlling data stored in a first volume of a first storage and a second volume of a second storage under one of an equivalent state and a non-equivalent state, the second storage being the same as or different from the first storage, the control apparatus comprising: a processor to determine, upon detecting a read error on the first volume under the non-equivalent state, a first storage area in which the read error has occurred, the first storage area being included in the first volume, determine whether a write process has been conducted on the first storage area under the non-equivalent state, determine whether a write process has been conducted on a second storage area under the non-equivalent state, the second storage area being included in the second volume and corresponding to the first storage area, and copy data stored in the second storage area to the first storage area when no write process has been conducted on the first storage area and the second storage area under the non-equivalent state.