Seagate 4TB SSHD Specifications

Seagate 4TB Consumer SSHD

Model Number





SATA 6Gb/s with NCQ

NAND Type/Size


DRAM Cache


Seek Average, Read (ms)


Seek Average, Write (ms)


Average Data Rate, Read


Average Data Rate From NAND, Read




Bytes per Sector


Predicted Annualized Failure Rate


Operating Power Usage


Idle Power Usage


Standby Mode


Sleep Mode



3-year limited



The drive itself is suitably well endowed to potentially provide fantastic performance.

Storage Test System

To test the drive properly we need a proper system that has the strongest I/O subsystem we can find. For the test we use the following components:

Seagate 4TB SSHD Performance Tests

The first test¬†that we’ll use will be that of HD Tune, a popular and rather stringent test that can go through the whole gamut of queue depths and is a very capable benchmark. In this we’ll simply run the benchmark screen as is once we open the program. The reported numbers will be the average read and write numbers.


A normal average for a disc HDD is between 120MB/s all the way up to 180MB/s. A typical NAS HDD can even achieve around 170MB/s thanks to optimizations and a fast platter speed. These are also sequential speeds, but even out of the box they aren’t necessarily a representation of the quickness over time due to how the controller puts most-used data on the NAND.

Next we’ll run the ubiquitous CrystalDiskMark, a test that also has a great degree of flexibility in how you can test. For this we opted to test the sequential read/write and a nominal QD of 32 with 1GiB of data to the drive. We do this sequentially and randomly. The numbers will be much lower for the random tests, as is expected.


Not being used in a normal setting, and just being benchmarked, the results are as expected. It’s not the fastest nor is it the slowest. The normal workload that most users will encounter are at QD32, so this bodes well. Random will always be slower and is limited by the literal speed that the platters spin at. Overall a good result.

The next test is a homemade test where a massive mixed-file folder that’s 33.8GB in size is transferred from one to the other. I’ve used HD Tune Pro to measure the results, including the time it takes to transfer the folder, the average IOPS during the transfer and, of course, the transfer speed itself. This is a write-only test. It’s a static Steam game folder that’s been placed elsewhere precisely for this test. It isn’t updated, so it can be used as a point of comparison in the future.


Since we have nothing to compare to as this is our inaugural HDD test, it’s still interesting and is something that you can compare to results and measurements at home. The write intensive test is still completed very well. As we collect more data, we’ll have a better idea of what runs better. To be sure, this didn’t saturate the SATA port, but it wasn’t slow either. Let’s take a look at the actual IOPS courtesy of IOMeter, a most impressive and very complex test. We set this to the most difficult QD that you might encounter to show a worst case scenario.


Though they seem quite low when compared to the speed demons that are SSDs, the IOPS that can be maintained are still impressive nonetheless. For the purposes of loading games from and doing the types of work that one would expect to regularly employ this HDD in, it’s fantastic. Far more than adequate.

Next we’ll measure response time, or the time it takes for a request to do something on the disk is acknowledged. For this we use HD Tune Pro again as the tool of choice to see just how long it takes to get the party started.

Seagate 4TB SSHD

12.3 ms from clicking the button (or dragging the file) to the actual action taking place isn’t terrible for this type of drive. Especially considering this is not coming from the NAND or a combination, but is just the drive. It has to be stressed that the benefits of the marriage of the two, especially when the amount of NAND is below 64GB, won’t be seen in normal benchmarks. To test that, we’ll need to consistently transfer and access specific files over time. Essentially, it’s a larger and faster cache in this case. And the benefits aren’t immediately apparent.

Where the NAND comes into play

Because it takes time to notice the difference, we’ve tested loading times of a game that was played consistently over seven days. The change in speed was noticed to be drastically faster on the seventh day, likely meaning that the most intensive assets were finally moved over by then with some being moved gradually as it became a priority. For this we used Star Wars: The Old Republic, as it’s a good MMO with lots of data stored locally. The measurement is in time, which is a very important metric for gamers.

Seagate 4TB SSHD

The results speak for themselves. They aren’t necessarily typical depending just how large the program is that you’re loading. But overall, it’s possible to have a significant increase in speed in commonly accessed things.


Seagate has an interesting proposition with their physical combination with their SSHD’s. The problem is that you don’t always immediately see the differences, and thus there’s an initial bit of disappointment when installing one. Even the benchmarks show us a very normal, though high performing, collection of platters and magnets. Where does that NAND come in? Where do we see it finally make a difference? It’s tough, because it’s “only” 8GB, which isn’t enough to have everything on there. After your activity is analyzed, and over a bit of time, the most important and most used bits are silently moved to where they’ll be more efficiently. It can work, and booting Windows takes but a few very small seconds to get to the lock screen. If you have a game that you play frequently, then those bits will load faster over time as well. Despite warnings, Star Wars: The Old Republic is a favorite of mine. Initially it took a full 23 seconds to load, but after seven days I measured it loading in 11 seconds instead. And this is from a cold boot, with nothing stored in memory. That’s a significant increase.

The drive is priced relatively high, though the actual real-world performance can surpass the WD Black line, if the NAND is used. Otherwise it’s an interesting bet. There’s a real benefit, but it may not be the best of prices. Overall it’s a solidly built drive with many benefits, though they aren’t always immediately apparent. If you wait for the drive to catch up to your behavior, then it’s a good drive. And reliability thus far has been quite high among those that are in the wild. It’s not the slowest and it’s not the most expensive, and it’s certainly something to look out for if you’re in the market.


Seagate 4TB SSHD Review
Seagate has a good formula with their SSHD's. The advantage isn't immediately apparent, but with patience you'll be rewarded with some very good performance for a very decent price.
General Features90%
What's Right
  • Great Mixed File Performance
  • NAND Actually Works Well
  • Good Real World Experience
What's Wrong
  • Performance Outside of Cache
90%Overall Score
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