Storage device and operating method thereof

Abstract

The present disclosure relates to storage devices. An example storage device includes a nonvolatile memory device that includes a plurality of memory blocks, and a memory controller that controls the nonvolatile memory device. The memory controller performs a soft erase operation on a first memory block among the plurality of memory blocks, measures a first cell count by applying a first reference voltage to a plurality of first memory cells selected in advance from a plurality of memory cells of the first memory block after performing the soft erase operation, generates a first health index associated with a retention characteristic of the first memory block based on the first cell count, and performs a reliability management operation on the first memory block based on the first health index.