There are three drive bays free for additional hard drives, as well as two available DIMM slots for additional DDR3 memory to supplement the included 16 GB. (pcmag.com)
Were the load time improvements done with additional hard drive cacheing? (blog.us.playstation.com)
There was a time when a geek with a media library had several additional hard drives packed into their PC, each of which were full of movies and seasons of TV shows — probably downloaded from unauthorized sources, because few legitimate sources existed in those days. (howtogeek.com)