|"Western Digital ELEMENTS 500GB WDBAAU5000EBK"|
Apparently that's a USB connected external drive.
Your data transfer speed may vary depending on which USB port you have it plugged into at the time.
USB device problems including for flash drives, external drives, memory cards.
External drive requirements.
See Response 1:
If you plug it into a USB 1.x port, the data transfer speed will be MUCH slower.
Even USB 2.0 ports will yield you a MUCH slower data transfer speed than a eSATA connected external drive.