Provided are an apparatus, system, and method to flush modified data from a first memory to a persistent second memory. A first memory controller coupled to the first memory includes at least one RAS controller to read a range of addresses in the first memory. In response to receiving a command from the power control unit, the at least one RAS controller is invoked to read data from at least one range of addresses specified for the RAS controller from the first memory. A second memory controller transfers data read from the first memory determined to be modified to the second memory. The first memory controller sends a signal to the power control unit to indicate that the modified data in the range of addresses specified for the RAS controller was flushed to the second memory in response to the RAS controller completing reading the range of addresses.