Review on West Digital 4TB Surveillance HDD - 5400 RPM SATA 6 Gb/s 64MB Cache 3.5in - WD Purple40PURZ (Old Version) by Cecilia Spencer

I used it as a hard drive in a surveillance DVR. It only failed after 2 ½ months. It started with typos and I reformatted it. It never worked again. Worst of all, this hard drive was a replacement for another purple WD that failed after just 18 months. Since my NAS has been working flawlessly with Seagate hard drives for over 2 years, I will switch brands. Western Digital just isn't reliable enough. Reading other reviews I think the heat is the problem. DVRs have poor ventilation and I think WDD drives are more heat sensitive than other brands. I replaced the hard drive with a Seagate one and installed better case ventilation in the DVR. Whether it's a ventilation issue or an issue with the WD drives, this seems to have fixed the issue.