Storage device and global garbage collection method of data storage system including the same

A storage device includes at least one nonvolatile memory device; and a memory controller configured to control the nonvolatile memory device, wherein the memory controller includes, at least one processor configured to control an overall operation of the memory controller; a buffer memory configured to store input/output data according to a control of the processor when an input/output request from an external device occurs; an error correction circuit configured to detect and correct an error of the input/output data; a garbage collector configured to selectively generate a first global garbage collection command in response to the input/output request and configured to perform a global garbage collection according to a second global garbage collection command received from the external device; and a storage interface configured to transmit the first global garbage collection command to another storage device.