Review on 🔒 Reliable Performance: Western Digital 4TB WD Red SMR NAS Internal Hard Drive - 5400 RPM, SATA 6 Gb/s, 256MB Cache, 3.5" - WD40EFAX by Troy Drake

So it turns out that all of these EFAX drives have a recording technology called SMR. The only thing you need to know about it is that it's incredibly slow. I can't give this back, although nowhere did they advertise that this disc has significantly different (and significantly worse) technology than before. When your WD Red drive announces 256MB cache, stay away!