The photo also shows five USB ports. I think they would be more appropriate for an external hard drive.
I have a USB 'splitter' in one of the USB ports on my computer. I have the keyboard and mouse plugged into the splitter along with a couple of USB flash drives to provide additional memory. I have an external hard drive plugged into another on-board USB port, and I have a separate DVD drive that I can also plug in if needed. There are additional USB ports on the front that I use for temporary connections - phone, camera, etc.