Western Digital 20TB WD Red Pro NAS Internal Hard Drive HDD - 7200 RPM, SATA 6 Gb/s, CMR, 512 MB Cache, 3.5" - WD201KFGX

I bought two units of the 20TB version of this WD Red Pro drive for my new storage system. I particularly went with the 20TB version, because - according to the datasheet on Western Digital's website - it is less noisy than some of the lower capacity models. I tested one of the units, not in my storage system, but in my open bench USB 3.0 to SATA Adapter (with a max transfer rate of over 500MBps). It performed well, the sequential read and write speeds as high as ca. 270 MBps and ca. 130 MBps on the low-side. This is typical of all HDDs: on the outside of the drive they can pack more data on one track than on the inside, so on each rotation they can write and read more data on the outside area of each disk platter. The write and read tests were also successful, no bad blocks were reported. For some performance figures, please see the attached screenshots (which have the serial number removed/redacted). Please note that the CrystalDiskMark results are performed on an empty HDD, so they seem to be executed in the "fast" section of the drive. The other graphs were taken from HDSentinel, relevant there are the bottom graphs, which show transfer rates across the surface of the drive. The sound of my test unit was also pleasant enough, the clicking wasn't too bothersome. But since I will move this drive into the case of my storage system very soon, the clicking will be a lot less noticeable than it is already. One action I always perform, BEFORE opening the product box of an HDD or SDD is to check the serial number on the box against the manufacturer's warranty website to ensure that the item is covered by the manufacturer's warranty. I do this both when amazon is the seller and when a 3rd party is the seller and amazon is just the fulfillment party. (I do not buy HDDs from a 3rd party seller that does not have fulfillment with amazon.) This is to avoid OEM/gray-market units that aren't covered by the manufacturer's warranty. A store warranty by a 3rd party seller is of no use to me, since these sellers come and go and I also don't want the hassle of dealing with them. Since the Red Pro series offers a manufacturer's warranty of 5 years, and HDDs fail frequently enough to make such a warranty very valuable, I always insist getting the manufacturer's warranty and even will query 3rd party sellers, if their stock with amazon is covered by such a warranty. As it turned out, the serial number of second 20TB HDD that I ordered (from a 3rd party seller, since amazon themselves were out of stock) did not show up in the manufacturer's database for U.S. warranty, so I can only assume that it is a gray-market unit and I immediately returned it. (I can only hope that the 3rd party seller will have to bear the full cost of this return, since I emailed them and asked about the manufacturer's warranty, before the item ever shipped, but they didn't answer my question.) One more tip: There has been some research that failure rates of HDDs from the same batch are somewhat correlated, so I always try to space out my purchases (either in time or by using different vendors) to increase the chance that I will be getting units from different batches. That's why I bought from two different 3rd party sellers on amazon (one of which apparently sold a grey-market unit), without disclosing that fact ahead of time.

Keeps making scrubbing sounds at all time. Won't be suitable for use in a home NAS device, if noise is a concern.

Great Product and really fast. 512 MB cache its a plus. I can recommend. Best for large NAS projects

Perfect, product was as described and delivered on time.

I’ve purchased this item 6 times, unfortunately three of them get failed without any warning signs. I’ve lost bulk of my important data. Reaching to WD support, simply replied they can’t support for replacement or provide any support to retrieve my lost Data even my HD’s warranty still valid. I’m totally disappointed and didn’t expect such kind of response. I don’t recommend to purchase as there is high risk of losing your data.