Storage device including storage controller processing command in which separate commands are merged and operating method thereof

A method of operating a storage controller, the method comprising:

• receiving a first Protocol Information Unit (PIU) including a first merge message from an external device;
• acquiring first data from the first merge message;
• storing, in a non-volatile memory device, the first data received from the external device;
• and
• reading second data stored in the non-volatile memory device,
• wherein the first merge message includes a merge Extra Header Segment (EHS) type.

A storage device comprising:

• a non-volatile memory device including at least a device data block;
• and
• a storage controller including:
• a Protocol Information unit (PIU) parser configured to receive, from an external device, a first PIU including a first merge message as a first Extra Header Segment (EHS), and acquire the first merge message by parsing the received first PIU;
• a PIU processor configured to perform, based on the first PIU, a sense operation of reading first data stored in a device data block of the non-volatile memory device, a select operation of storing, in the device data block, second data received from the external device, or both the select operation and the sense operation;
• and
• a PIU generator configured to generate a second merge message according to the first merge message, and transmit a second PIU including the second merge message to the external device, wherein the second merge message includes a merge EHS type, first status data indicating that the select operation has succeeded, second status data indicating that the sense operation has succeeded, and the second data.