Storage device

A storage device comprising:

• a nonvolatile memory device comprising a plurality of memory blocks,
• wherein each of the plurality of memory blocks is divided into a plurality of zones and is formed on a substrate, and
• wherein each of the plurality of zones comprises one or more word lines;
• and
• a controller configured to:
• perform a reliability verification read operation on a first zone of the plurality of zones of a memory block selected from the plurality of memory blocks if a number of read operations performed on the first zone reaches a first threshold value;
• and
• perform the reliability verification read operation on a second zone of the plurality of zones of the selected memory block if a number of read operations performed on the second zone reaches a second threshold value,
• wherein the controller is configured to classify the plurality of memory blocks into a plurality of new zones based on a number of program/erase cycles of the selected memory block.

A storage device comprising:

• a nonvolatile memory device including a plurality of word lines vertically stacked on a substrate,
• wherein each of the plurality of word lines is associated with one of a plurality of zones divided according to a height of each of the plurality of word lines from the substrate;
• and
• a controller comprising a count management unit storing a plurality of threshold values each of which is associated with one of the plurality of zones, generating a plurality of read counts by counting a read command for each of the plurality of zones and performing a reliability verification read operation on one or more word lines associated with a first zone of the plurality of zones if a read count of the first zone is greater than a threshold value of the first zone.