Sequential Read Performance

Our first test of sequential read performance uses short bursts of 128MB, issued as 128kB operations with no queuing. The test averages performance across eight bursts for a total of 1GB of data transferred from a drive containing 16GB of data. Between each burst the drive is given enough idle time to keep the overall duty cycle at 20%.

Burst 128kB Sequential Read (Queue Depth 1)

The burst sequential read performance of the Samsung SSD 850 120GB places it in the second tier of 120GB-class drives, but it's actually the fastest of the current models. The performance is a clear improvement over the 850 EVO but is about the same as the 750 EVO and the HP S700.

Our test of sustained sequential reads uses queue depths from 1 to 32, with the performance and power scores computed as the average of QD1, QD2 and QD4. Each queue depth is tested for up to one minute or 32GB transferred, from a drive containing 64GB of data.

Sustained 128kB Sequential Read

On the longer test of sequential reads, the Samsung 850 falls well below the standard set by Samsung's earlier drives and ends up slightly slower than the HP S700. The S700 Pro and ADATA SU800 are in last place with less than half the performance of the 850 120GB.

Most drives show no performance scaling with queue depth on the sequential read test. The older Samsung drives all show some improvement from QD1 to QD2 and are steady after that, while the 850 120GB is simply the same speed across the board.

Sequential Write Performance

Our test of sequential write burst performance is structured identically to the sequential read burst performance test save for the direction of the data transfer. Each burst writes 128MB as 128kB operations issued at QD1, for a total of 1GB of data written to a drive containing 16GB of data.

Burst 128kB Sequential Write (Queue Depth 1)

The short burst sequential write speed of the Samsung SSD 850 120GB is comparable to Samsung's other drives in this capacity class, and is better than any other current drive for this segment.

Our test of sustained sequential writes is structured identically to our sustained sequential read test, save for the direction of the data transfers. Queue depths range from 1 to 32 and each queue depth is tested for up to one minute or 32GB, followed by up to one minute of idle time for the drive to cool off and perform garbage collection. The test is confined to a 64GB span of the drive.

Sustained 128kB Sequential Write

On the longer sequential write test, the Samsung SSD 850 120GB is tied for second place, though the performance of the 850 PRO far outshines everything else.

As with sequential reads, most of these drives handle sequential writes at the same speed regardless of queue depth. The 850 PRO is the only one to show substantial improvement as queue depths increase. Several other drives experience temporary hits to their write performance as a result of their SLC write caches filling and forcing the drive to perform garbage collection, but most are steady through most of the test.

Random Performance Mixed Read/Write Performance
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  • Kristian Vättö - Monday, November 27, 2017 - link

    There are still MLC based enterprise SSDs from Samsung, such as SM863a.
  • yifu - Saturday, December 2, 2017 - link

    also Toshiba hk4r
  • qlum - Monday, November 27, 2017 - link

    For the pc's at work I always use 120gb ssd's as they offer enough capacity and are still about €20 cheaper then 200gb+ drives.
  • bug77 - Tuesday, November 28, 2017 - link

    I'm not sure giving up 80GB (40%) space to save €20 is the right choice. Remember, these things don't like being full and people tend to save a lot of junk of their drives.
    That said, the smallest SSD is still way better than the fastest HDD. (Have you ever seen Win10 trying to patch itself while installed on a HDD?)
  • ads295 - Tuesday, November 28, 2017 - link

    I think that's why laptops started skipping on the HDD activity LED from as early as when Win8 was available.
  • bcronce - Tuesday, November 28, 2017 - link

    Great for my firewall. I only need ~4GiB of space.
  • Glaurung - Tuesday, November 28, 2017 - link

    "Remember, these things don't like being full and people tend to save a lot of junk of their drives."

    For situations where the drive is never going to be full and you just need the cheapest possible SSD, it's fine. For instance, My spouse writes reports for a living, and she has never come anywhere near to filling up the 40gb X25-V on her work laptop. (no music, no pictures, no videos, just documents and PDFs and audio recordings that she refers to and then deletes when the report gets final client approval).
  • pixelstuff - Monday, November 27, 2017 - link

    We've been missing the 128GB 850 Pro model with it's 10 year warranty, which usually cost about $90. We were using it in single task devices such as DVRs with secondary data drives. Having to move to the 256GB 850 Pro just meant we had to spend an extra $30+ for no extra benefit, and unfortunately those 256GB drives never dropped to the $90 price range.
  • mapesdhs - Wednesday, November 29, 2017 - link

    Pricing did drop that low at one point; in the UK the 850 EVO 250GB was 53 UKP from Amazon and not much more elsewhere (meanwhile, 500GB pricing was slowly heading down to 100 UKP), but then after a blowout sale of several thousand 850 EVO 500GB units by one retailer in two weeks at around 115 UKP each (I bought two), I'm sure Samsung realised they simply didn't need to sell their tech so cheap, prices went up, and all the other vendors followed suit. Also, when new models came out, old models were almost immediately removed from seller sites, sometimes on the same day. Since then, pricing has almost doubled, there's just no need for the manufacturers to offer low pricing when they can easily sell everything they make due to OEM demand. It's ironic that the nature of that demand is largely by a consumer demographic that treats tech as thoroughly disposable, and often has little regard for what it is or how it works.

    The more I see new products like this being worse than old products, the more I'm impressed with what Intel has done with Optane, etc. At least Intel has actually done something new, whereas Samsung seems to have done what Intel did with its CPU-based strong position, ie. sat on its butt for several years while the cash rolled in and not bothered to innovate. Have to wonder why Samsung couldn't have brought ought something like Optane ages ago, and for the consumer market, not just Enterprise. Yes there's a shift towards NVMe, but it's not that big yet (with warranties 50% shorter and insane price hikes on retail versions), and a lot of consumers just want capacity with decent quality. At this point a 4TB SATA SSD with the quality level of the 850 EVO would sell very well if sensibly priced, but nobody's even trying, they're still having fun selling low capacity models (why sell one 4TB when one can make a lot more selling twenty 120GB units). I remember SanDisk promised to have an 8TB model by now, but that never happened.

    Billy, add the old 840 and 840 Pro into those results charts, I bet this new 850 wouldn't look so impressive, ditto if other old models were included too like the Vertex 4, Vector, Neutron GTX, etc. Heck, even the old 830 would likely put most of the modern non-Samsung models to shame (ditto something as ancient as a Vertex3, and it'd be hillarious too see where the budget Agility3/4 would fit in the charts today). SATA SSDs have become like CPUs before Ryzen finally launched, the tech has stagnated or even gone backwards. The 750 was touted as a cheaper 850 EVO, but in reality it became more expensive. I get that the nature of parallelism in NAND means larger dies don't offer the performance at lower capacities, but then that's why it would make sense to create something genuinely new; Intel needed a good poke in the ribs from Ryzen to get moving again with its CPU line, but at least it *did* something with respect to developing new storage tech.

    Ian.
  • WithoutWeakness - Monday, November 27, 2017 - link

    First section header in the introduction: The *Samung* SSD 850"

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