Until recently I had a WD My Book Essentials 500GB unit that I was using as an EHD with my 622, and it worked flawlessly. Then it died without warning about 2 days after the one year warranty expired. Maybe I just had bad luck, but then again, maybe not. The next one I get will not be in a plastic case. I am going to go the DIY route and get an internal drive and a good enclosure.