A storage device includes a first memory device, a second memory device and a storage controller. The first memory device buffers a plurality of unit time interval data. The plurality of unit time interval data are received in each of a plurality of monitoring time intervals. The second memory device stores at least one of the plurality of unit time interval data. The storage controller controls an amount of data flushed from the first memory device to the second memory device based on one of first and second flush commands. The storage controller compares a shock measurement value representing a magnitude of an external shock with a shock reference value. When the shock measurement value is less than or equal to the shock reference value, the storage controller provides the first flush command to the first memory device to flush first unit time interval data.