US Patent 10423485 Memory system and operation method thereof

A memory system may include: a nonvolatile memory device comprising a plurality of memory blocks; and a controller suitable for checking a read operation time, a read level class, an error occurrence, and an error occurrence class when performing the read operation on each of the memory blocks, classifying the memory blocks into various classes based on a result of the checking, and differently setting a durability parameter for each of the memory blocks based on a result of the classifying of the memory blocks.