WD Red Plus 4TB NAS Hard Disk Drive - 5400 RPM Class SATA 6Gb/s, CMR, 64MB Cache, 3.5 Inch - WD40EFRX

Pros: As usual, shipping time from newegg.com was expeditious and the hard drives (quantity of 2) arrived undamaged and very well packaged. Once I opened the shipping box, the inside revealed air cushion fillers and 2 WD-branded cardboard boxes. Each WD cardboard box contained a Hard Drive in a shock absorbing cradle. I was very happy with the shipping.
- WD Red NAS hard drives are recommended by the manufacturer for use in home and small office NAS systems with 8 or less Hard Drives.
- I have had 2 of these 4TB Hard Drives installed in my Seagate STDD4000100 NAS Pro 2-Bay Network Storage (Newegg items N82E16822178609 and 9SIA2W02VG7768). I removed 2 of my old hard drives from my NAS and I have replaced them with two new hard drives (each is 4 TBs). I then went through “diskless” setup of my Seagate NAS, which took about 20 minutes. The NAS needed to download new firmware and the hard drives were reformatted and I set them up in JBOD set up. The formatted capacity showing by my NAS was 7.9 TB.
- After prolonged use and multiple large data transfers, the NAS reports Hard Drive temperatures of 41 and 42 degrees Celsius. I transferred large amount of data in multiple folders (about 40 gigabytes worth) back and forth between my rMBP and my NAS using wireless AC connection. Much to my surprise, large data transfers did not raise temperature of my hard drives.
- NASware 3.0 is preinstalled.
- 3-year limited warranty is pretty generous.
- Interface speed: SATA 6 Gb/s.
- Internal transfer rate/speed up to 150 MB/s. In real life I was clocking sustained transfer rates of about 108 to 117 MB/s over gigabit ethernet (desktop PC) and ac wireless (rMBP).
- Drives seem quiet.

Cons: - When I tried to register these drives with WD for warranty purposes, I received “out warranty” status for both drives, even though they were manufactured in January of 2016. I opened “service case” with WD customer service and they were very quick to update warranty information for my drives. My new warranty expiration date is March of 2019.
- I suggest you keep your receipts, check your serial numbers and make sure your warranty information is correctly recorded by the manufacturer.

Overall Review: - I was very pleased with the drives through out my testing. The installation process was painless, the drives are quiet and did not run hot in my NAS. The transfer rates are good. The drives are designed for prolonged use in NAS setup. The warranty is generous. WD brand is well known and price is competitive for the quality they offer. I have used these drives for about 3 weeks in my NAS. I have encountered no problems. Right now, I trust these drives with my personal data.
- If you need spacious drives for your NAS, you can’t go wrong with the WD WD40EFRX drives.

Pros: Despite being 5400 RPM drives, they are able to produce peak sequential reads above 120MB/s, and the random reads aren't that bad either.

Cons: I'm getting sata bus errors when the drive is connected at 6gbps and under load. Usually dmesg shows failed commands resulting in a sata bus reset. For a drive meant to operate unattended for long periods of time, this is a concerning issue that makes me wonder how solid the control board on the drive is.

Have RMA'd one of the 2 drives I bought because of it, but the replacement device is producing the same errors. Currently trying
libata.force=3.0G in the kernel options to slow the sata bus down to 3gbps in the hopes of eliminating this error. If this fails I will have to return these drives and get WD RE devices instead.

Overall Review: A household or small business NAS device might be okay with these. The problem is not obvious in normal use, and many commercial NAS controllers are not capable of reaching speeds that would cause this error.

I'm not so sure now on having them in a small business server, and will be watching what they do.