This month an Xbox One software upgrade brings on the ability to work with an external hard drive. With this ability, users have been testing multiple different types of drives to see which work quickest. Inside the standard Xbox One is a Samsung 500GB 5400 RPM (M8 ST500LM012) working with the machine’s standard SATA2 connection - with USB 3.0 connecting your drive to the board, providing one reason why this external method may be significantly quicker - or so it would seem.
In one test done by NeoGAF member Hawk269, he used a 4TB Seagate HD running at 5400RPM - the same speed as the Samsung device inside the Xbox One. Because the Seagate drive works with a much higher data density, higher transfer rates are inevitable.
USB 3.0 and SATA2 are able to provide speeds far quicker than any HDD - aka the connections are not what’s important here. Instead it’s down to the drive you use, and the drive’s ability to blast out the data at high rates.
Another user submitting results to an official Xbox Forums site showed significant time savings with a StarTech RAID enclosure sporting RAID 0 2 4GB (7.2TB) west dig black drives - aka far higher density than what’s inside the Xbox One again. Get denser, load quicker.