Operation method of nonvolatile memory device and storage device

A method of operating a nonvolatile memory device including a plurality of memory cells, the method comprising:

• receiving a read command from a memory controller;
• in response to the read command, performing a multi-sensing read operation based on at least two reference voltages;
• in response to the read command, adjusting at least one of first through nth read voltages (n is a natural number greater than 1) based on a first result of the multi-sensing read operation;
• and
• in response to the read command, performing, based on the first through nth read voltages, a read operation corresponding to the read command with respect to the plurality of memory cells.

A storage device comprising:

• a nonvolatile memory device including a plurality of memory cells and reading data stored in the plurality of memory cells based on first through nth read voltages (where n is a natural number greater than 1);
• and
• a memory controller configured to transmit parameters including information about a read voltage level change of each of the first through nth read voltages after transmitting a read command and an address to the nonvolatile memory device,
• wherein, in response to the read command, the nonvolatile memory device is configured to:
• perform a sensing operation with respect to the plurality of memory cells based on a reference voltage,
• perform a cell counting operation based on the sensing operation,
• adjust at least one read voltage of the first through nth read voltages based on a result of the cell counting operation and the parameters, and
• read data stored in the plurality of memory cells based on the adjusted at least one read voltage.