Western Digital6TB WD Red Pro NAS Internal Hard Drive HDD - 7200 RPM, SATA 6 Gb/s, CMR, 256 MB Cache, 3.5" - WD6003FFBX

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.

I only trust wd and Samsung drives.

Using 2, 4TB drives in a home RAID array for photos, videos, etc. Main drive is an SSD but decided to go with these for bulk storage as they are a bit cheaper (guessing my last time buying HDD's and next time will just use SSD's because they are just so much faster).Drives seems to perform nicely and other than a little HDD noise here and there don't find them bothersome at all. Previously had 2, 2TB of these red drives in a RAID array (had it running for about 8 years) and never had any issues. In our office we have Gold versions of these running on a backup server for about 6 years with no issues. All in all, very reliable. Speed is fine, but obviously not going to compare to SSD.One thing about size of the drives which I see some comments on...The size of the 4TB drive is going to be approximately 4 trillion bytes (mine is 4,000,765,177,856 bytes), however your system will likely report that as 3.64 TB or 3.726 GB. The reason for this is that Windows computes 1GB as equal to 1,073,741,824 bytes and 1TB as equal to 1,099,511,627,776 bytes. These numbers are achieved by raising 2 to an increasingly greater power till you get your first number in the billions and then trillions. There is some technical reason why this is done, but ultimately it is just confusing as it creates 2 different ways of computing size. One, counting the actual number of bytes and the other, dividing your bytes by one of those numbers to get the amount of GB's or TB's. For MB the number Windows uses is 1,048,576 bytes (for example a 20,000,0000 byte file will be reported as 20,000,000 / 1,048,576 = 19.07MB).In any case, here is a summary of the approx drives sizes and around what Windows will report the size as (assuming the drives sizes represent actual bytes exactly, so 4TB for this calculation will be 4,000,000,000 bytes and not the number my computer showed above... so expect the actual numbers to be slightly higher than these):2TB Drive = 1.82TB or 1,862.65GB4TB Drive = 3.64TB or 3,725.29GB6TB Drive = 5.46TB or 5,587.94GB8TB Drive = 7.28TB or 7,450.58GB10TB Drive = 9.09TB or 9,313.23GB20TB Drive = 18.19TB or 18,626.45GBHope this clears up some confusion here.

I been using multiple of these drives for a number of months without any problems. The drives are relatively quiet and have been error-free. Data transfer rates are what I would expect.

First one died in a couple of weeks. Good warranty support. Replacement is running well.