Provided are a method, system, and article of manufacture for determining whether data written to source storage locations according to a write order is copied to corresponding target storage locations in the write order. Values are written to indicated source storage locations in a write order. The values written to the source storage locations are copied to corresponding target storage locations. The values at the target storage locations are read and a determination is made from the read values whether the values were written to the target storage locations in the write order.