Replacement of failed memory unit with redundancy memory unit in a memory device and method thereof

A method for operating a memory device, comprising:

• determining a target memory unit that has failed from among an M number of memory units;
• generating a command that requests replacement of the target memory unit with a target redundancy memory unit from among an N number of redundancy memory units;
• and
• transmitting the command to a volatile memory that includes the M number of memory units and the N number of redundancy memory units,
• wherein each of M and N is a natural number of 2 or greater.

A memory device comprising:

• a volatile memory including an M number of memory units and an N number of redundancy memory units;
• and
• a volatile memory controller including a nonvolatile memory that stores mapping information that includes mapping of a failed target memory unit from among the M number of memory units to a replacement target redundancy memory unit from among the N number of redundancy memory units,
• wherein the volatile memory controller reads, upon power-on, the mapping information stored in the nonvolatile memory, and transmits the mapping information to the volatile memory,
• wherein the volatile memory includes a mapping unit that stores the mapping information received from the volatile memory controller after power-on, and
• wherein each of M and N is a natural number of 2 or greater.