A method of operating a data storage device in which a nonvolatile memory is included and a mapping table defining a mapping relation between a physical address and a logical address of the nonvolatile memory is stored in a host memory buffer of a host memory includes requesting a host for an asynchronous event based on information about a map miss that the mapping relation about the logical address received from the host is not included in the mapping table, receiving information about the host memory buffer adjusted by the host based on the asynchronous event, and updating the mapping table to the adjusted host memory buffer with reference to the information about the host memory buffer. A method of operating a data storage device according to example embodiments of the inventive concept can reduce the number of map misses or improve reliability of a nonvolatile memory.