An operating method of a data storage system comprising a processor and multiple storage devices, the operating method comprising: a first storage operation of selecting a first storage device, a second storage device, and a third storage device among the multiple storage devices and transmitting and storing data generated by the processor in the first storage device and the second storage device, a second storage operation of transmitting, to the third storage device, the data stored in the second storage device and compressing and storing the data in the third storage device, a first access operation of accessing the data in the first storage device, by the processor, after the first storage operation is completed, and a second access operation of accessing the data in the second storage device after fail of the first access operation.