Storage device and operating method thereof

Abstract

A storage device includes a memory device and a memory controller. The memory device stores a history read table including root bit information, read voltage information, and error bit information on each of a plurality of memory blocks, and performs a read operation of reading data stored in the plurality of memory blocks based on the history read table. When the read operation fails, a memory controller changes a level of a read voltage, and controls the memory device to perform a read retry operation of retrying the read operation by using the changed read voltage. When the read retry operation passes, the memory controller determines whether the history read table is to be updated by comparing the root bit information of the read retry operation with the root bit information of the history read table.