Storage device and operating method thereof

An operating method of a storage device including a nonvolatile memory, a controller, and write buffers, the operating method comprising:

• receiving, by the controller, a write request and write data from a host;
• acquiring, by the controller from the write buffers, buffer usage information including an available size of the write buffers;
• setting, by the controller, a response transmission delay time based on the available size of the write buffers, a minimum response transmission delay time, and a maximum response transmission delay time;
• transmitting, by the controller, a response to the write request to the host after the set response transmission delay time passes;
• and
• dynamically adjusting, by the controller, as the available size of the write buffers changes, the response transmission delay time within a range from the minimum response transmission delay time to the maximum response transmission delay time.

A controller for controlling a memory device, the controller comprising:

• a write buffer configured to buffer write data to be stored in the memory device;
• a command queue configured to queue a write request corresponding to the write data;
• a response delay configured to respond to the write request according to an actual response transmission delay time based on a total size of the write buffer, a threshold usage size of the write buffer, a currently available size of the write buffer, and minimum and maximum response transmission delay times;
• and
• a processor configured to control the memory device to store therein the write data in response to the write request.