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Samsung 850 Pro 2TB

Samsung 850 Pro 2TB Review – Performance or capacity. That’s been the dichotomy that’s dominated data storage since the first mainstream solid-state drives appeared nearly a decade ago. But now Samsung has launched the first 2TB SSDs aimed at consumers. Give it up for the Samsung 850 Pro, tested here, and its 850 Evo sibling. At last, the speed of solid-state flash has been combined with the multiterabyte mass storage that’s previously been the preserve of conventional hard drives and their spinning magnetic platters.

Samsung-850-Pro-2TB Samsung 850 Pro 2TBHow has Samsung done it? It’s largely down to its 3D V-NAND memory, the trailblazing flash memory tech that sees memory cells stacked atop one another, rather than arranged in a flat, 2D array. The obvious benefit is the ability to squeeze much more capacity into a given area. But the upsides go further. Using multiple layers of memory cells, for example, takes the pressure off the need for each layer to absolutely maximise capacity.

That means mature rather than cuttingedge silicon production processes can be used, increasing yields and reducing costs. It also means the chips aren’t on the ragged edge for performance, making them more reliable, often a major limitation for flash memory that wears out gradually as data is written to the memory cells. In practice, that means that where Samsung’s previous-gen 840-series drives sported NAND memory with tiny 19nm transistors, the 850 series gets by with 40nm tech.

To achieve the headline-grabbing 2TB capacity, Samsung hasn’t had to weave too much magic on the memory front, but it has had to come up with a new controller chip. Samsung says its existing MEX controller – as seen in the existing 128GB to 1TB 850 Pro SSDs – had limitations when it comes to really high capacities. Consequently, the new 2TB has a new controller, the MHX.

Samsung’s performance claims suggest the increased capacity doesn’t incur any performance downsides. It quotes exactly the same numbers for the new 2TB 850 Pro as existing Pros down to 250GB. So, that’s 550MB/s sequential reads, 520MB/s sequential writes, plus 100,000 Read IOPS and 90,000 write IOPS.

Staying power

Where things get really interesting is durability. The 2TB absolutely does not disappoint. Samsung provides a mega 10- year warranty, along with expectations of 300TB-worth of writes. Wow. That’s probably even more important with a really large drive than a puny SSD, which you might expect to replace within a couple of years. This thing has legs.

However, the elephant in the room is that the 2TB model, and indeed all Samsung 850 Pro and Evo models, don’t offer compatibility with the latest storage interfaces. We speak of PCI Express-based interfaces like M.2 and SATA Express. The 850 Pro 2TB is a plain, old SATA drive.

That means it’s limited to a real-world peak performance of 550MB/s. That’s simply a function of the 6Gb/s limitation of the SATA interface. What’s more, SATA uses a control protocol known as AHCI, which was conceived for magnetic hard drives, not SSDs. That, in turn, makes SATA sub-optimal in terms of random access performance with SSDs.

If you’re upgrading an existing system – and particularly a laptop – that shouldn’t be a problem. You may not have any M.2 slots in your PC, anyway. But as the storage solution for a new PC you’re building, or for an existing system with M.2 support, the limitations of SATA are more of a problem. Compared with the near-2GB/s of bandwidth being kicked out by M.2 drives, the 550MB/s top whack of a SATA drive makes even this 2TB drive look old hat.

Samsung’s figures are born out in testing as well. In terms of raw sequential throughput, it’ll do 559MB/s for read and 534MB/s for writes. In other words, it’s simply bouncing off the limitations of the SATA interface. As for random access performance, we’re talking 41MB/s for reads and 133MB/s for writes, which are again as good as it gets for a SATA drive.

Arguably more interesting is the fact the 850 Pro 2TB clocks in with probably the fastest time we’ve seen for a SATA drive in our real-world 5GB file compression test. It’s only a matter of a second or two, but it’s further confirmation that this drive is about as good as it gets for SATA technology.

For context, the latest M.2 drives are up near 2GB/s for sequential reads and 200MB/s for 4K random writes. So, how you view this drive’s performance ultimately comes down to whether you’re in the market for an M.2 or a SATA drive. It’s great for a SATA drive, but it can’t really get close to a drive built around the latest standards. That’s a tough pill to swallow when being asked for £750.

Viewed in the broad context of all SSDs, the new Samsung 850 Pro 2TB is dead slow. The latest M.2 drives absolutely annihilate it for raw performance. However, narrow the context down to SATA drives and it suddenly finds itself at the very top of the pack. So, it really comes down to your buying needs and preferences. If you need the biggest and best SATA SSD for something like a laptop upgrade, this new Sammy is a killer.


  • Serious storage
  • Stellar endurance
  • Great for laptops
  • Fast for SATA


  • Seriously expensive
  • Limited by SATA interface

Samsung 850 Pro 2TB Specifications

  • Capacity 2TB
  • Memory type 3D VNAND
  • Controller Samsung MHX
  • Interface SATA 6Gb/s
  • Form factor 2.5-inch
  • Warranty 10 years limited

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