This seems to be the best technical discussion of the issue that I've found so far, so I'm jumping in even though I'm using a different platform. I'm having the same issue with these drives, but I have a slightly larger sample set to play with an I've found a pattern in my case. I'm using a Synology NAS with several Western Digital Red Pro drives. I'm seeing that - with flawless consistency - only certain a model number exhibits this problem. I'm also seeing that this model number is explicitly not listed in Synology's hardware compatibility list, even though other Western Digital Red Pro drives of the same capacity are. So I'm strongly suspecting that there is either a hardware or firmware issue with certain models. In my case, I have: WD6002FFWX-68TZ4N0 - NOT Reliable WD6003FFBX-68MU3N0 - Reliable WD6003FRYZ-01F0DB0 - Reliable I'm also noticing that the issue occurs on very hot days. The room temperature only varies by a few degrees (yay air conditioning), but again it's a very consistent pattern. We don't have any wall outlet under-voltage issues; our utility power is extremely clean here. We also monitor it with our UPS and ATS systems. Hope this helps.