A method of controlling a non-volatile memory system including a non-volatile memory device having a non-volatile memory cell array is disclosed. The method includes: determining environment information corresponding to a communication speed relating to a transmission medium to which the non-volatile memory device is connected; selecting a management operation mode based on the determined environment information; and performing a memory managing operation on the non-volatile memory device using the selected management operation mode during an idle time of the non-volatile memory device.