Seagate 4TB IronWolf NAS SATA Hard Drive 6Gb/s 256MB Cache 3.5-Inch Internal Hard Drive for NAS Servers, Personal Cloud Storage (ST4000VN008), Silver

Pros:- No issues with test, installation, or data transfer- Work well with Enterprise level Adaptec RAID card- Good features on the 4TB and larger drives- Personally experienced long term reliability of Seagate drives (Used Seagate for years, 25+ drives from 40GB to 3TB prior to this purchase)Cons:- Had to spring for the 4TB drives or larger to get the rotational vibration sensors (unavailable on smaller capacity Ironwolf drives)Even though I have been using Seagate drives almost exclusively for all of my spinning disk drives, I was open to using any reliable manufacturer to replace my six 1TB Seagate drives with four 4TB ones. My drives run in a RAID 5, with a spare, in my personal server and longevity is important. I usually run drives 24/7 for about 5 years before they are replaced.I was very close to purchasing four W brand drives due to the positive reviews, but finally settled on Seagate because most of the failures of Seagate drives seemed to be "infant mortality" failures (happen very early in the product life), where the W brand drives seemed to fail more often around a year after purchase (based on reviews on Amazon). This was true when I ordered prevously ordered a Seagate 3TB backup drive and it had failed out of the box. It was much more convenient for me to run hours of testing on each drive before installing them and replace them early rather than having the drives work well for a year and then having to submit a warranty claim.When I received the drives, I ran approximately 13 hours of testing on each 4TB drive by performing a Long test using the Seagate tool. I checked the SMART data before and after and this test seemed to read all of the data from the entire drive because the SMART data after the test stated that 4TB of data had been read. Because of my RAID 5 and my backup strategy, this was enough for me to depend on the drives in my server and I installed them.I configured the RAID 5, restored the backed up data to the drives, and then performed a build/verify on the RAID. The data transfer from the backup of my 2.3TB of data was much quicker than I expected and my server was back up and running. The drives are not louder than some of the loud parts of my server (server fans and a 300GB 15k RPM SAS OS drive), so I would not be able to provide details to how loud the drives are. The performance is improved over my six 1TB Barracuda 7200 RPM drives and I am pleased with how the transition was.

I was between this, the HGST and WD RED 4TB NAS HD's for my Synology DS212J. I, like I tend to do, agonized for a long time before deciding which to purchase. At the time I bought these (cyber monday 2016) the HGST was the same price as the Seagate Ironwolf, and the WD Red was $15 more. After extensive review reading, spec reviewing, etc. I decided to go with this drive. My reasoning behind this was the fact that this was a newer generation drive with technology integrated to provide more features and benefits related to NAS use than competitor NAS drives. Also, for the supposed 1% failure rate of the HGST I was surprised to see as many negative reviews as I did. Red's seemed like a coin toss to me.Seagate has done a lot to improve the reliability of their drives in order to stay competitive in this market. I felt confident in my purchase, and I still do.The last (2) Hard Drives I put in this Synology NAS were 1TB WD Blacks. Both of the failed immediately out of the box and had to be RMA'd (purchased from Newegg). I know black wasn't correct for NAS, but at the time I purchased the NAS I wasn't exactly flush with cash so I bought what I could afford. I left them as separate volumes with no RAID or JBOD, that way if one failed only the data on it would be lost. Both of the replacement WD Blacks have lasted since December 2012. One of them will now only write at 12MB/s, but is otherwise okay, and the other one is in perfect working order. Over the years the data on those drives become more and more important. I decided that it was time to upgrade to a decent capacity and to go RAID 1 for redundancy data protection.The Synology took almost a full day per drive to perform it's initialization and error checking process but both of these Seagate 4TB Ironwolf drives work flawlessly. They operate quiet as well.The only con is the write speeds. The WD Blacks I had were 7200rpm and the 4TB version of the Seagate Ironwolf is only 5900RPM. I've got gigabit Ethernet and other than the drives, no other variables have changed. The fully functioning WD black I could write on, from my PC over the wired network, to the tune of about 20MB/s. The weak WD Black could only write about 12MB/s. The Ironwolf is 10MB/s. Now it should be noted that before the WD Blacks were individual volumes and not in RAID. These Ironwolf drives are in RAID 1 so that may cause a little slow-down on the write speeds I suppose.I'd recommend, to anyone who could afford it, to get this drive in either the 6TB (because it's 128MB cache and 7200rpm) or 8+TB (because it's 256MB cache and 7200rpm). If you're like me, and money is a consideration and you're willing to sacrifice a little speed to get a better dollar to terabyte value then you really can't go wrong with the Seagate Ironwolf 4TB (lower capacities not a better value at current $:TB).Edit 12-30-16: I'm not really sure what happened because I haven't changed anything but the consistent write speed of a large video file (3GB+) is about 19MB/s and smaller files (like 300MB) are like 22-25MB/s. Obviously the initial burst is higher, but this is what the data transfer speed drops to once it settles down.

I have... let's see... two 2 TB Iron Wolf's (left over now), four 4 TB Iron Wolf's, four 6 TB Iron Wolf's, and four 12 TB EXOS X16 drives, (if you want to count those.) To make this work the best way possible, I had to order two more of the 4 TB drives. (I already had two - in a really weird combination RAID with the 2 TB drives.) They got here and I put them in one of the NAS's with the other 2 and it's synchronizing them right now -- FLAWLESS, as usual! They came in an electrostatic bag, in a sausage link-sized bubble wrap thing I've never seen anything like! Superbly packaged. All that so I can say: I have NEVER had EVEN ONE problem with an Iron Wolf (or an EXOS) hdd. I need more stars to give them. And, at least in an Asustor NAS or a Synology NAS, there's no beating the SMART monitoring.

I ordered two 4tb for my NAS and was impressed by the speed at which they were delivered, the way they were packaged and the ease of installation. I would definitely buy again.