Storage device monitoring and storing on cell counts of blocks and operating method thereof

A storage device comprising:

• a non-volatile memory comprising a plurality of blocks;
• a plurality of word lines arranged in each of the plurality of blocks;
• a buffer memory;
• and
• a controller configured to,
• periodically read memory cells connected to a reference word line by applying a read level to the reference word line,
• periodically update an on-cell count in the buffer memory, the on-cell count indicating a number of memory cells, which are turned on by applying the read level to the reference word line, from among the memory cells connected to the reference word line,
• wherein one of the plurality of word lines is selected as the reference word line based on vector-based similarities between the plurality of word lines.

An operating method of a storage device, which includes a non-volatile memory comprising a plurality of blocks, a plurality of word lines arranged in each of the plurality of blocks, a buffer memory, and a controller, the method comprising:

• selecting reference word lines from the plurality of word lines arranged in each of the plurality of blocks based on vector-based similarities between the plurality of word lines;
• sequentially monitoring, by the controller, on-cell counts of the plurality of blocks by reading memory cells connected to the reference word lines of the plurality of blocks of the non-volatile memory by applying a read level to the reference word lines;
• and
• storing, by the controller, the on-cell counts of the plurality of blocks in the buffer memory, the on-cell counts indicating a number of memory cells, which are turned on by applying the read level to the reference word lines, from among the memory cells connected to the reference word lines.