Burst IO Performance

Our burst IO tests operate at queue depth 1 and perform several short data transfers interspersed with idle time. The random read and write tests consist of 32 bursts of up to 64MB each. The sequential read and write tests use eight bursts of up to 128MB each. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

QD1 Burst IO Performance
Random Read Random Write
Sequential Read Sequential Write

Our burst IO tests show little to no performance differences between the Samsung 870 EVO and other top SATA SSDs. The 1MB sequential transfers are already hitting the SATA throughput limits even at QD1, and the 4kB random IOs are at best marginally improved over Samsung's previous generation. Samsung's slight improvement to random read latency is enough to catch up to Micron's as shown by the Crucial MX500, but a 10% gain hardly matters when NVMe drives can double this performance.

Sustained IO Performance

Our sustained IO tests exercise a range of queue depths and transfer more data than the burst IO tests, but still have limits to keep the duration somewhat realistic. The primary scores we report are focused on the low queue depths that make up the bulk of consumer storage workloads. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Sustained IO Performance
Random Read Random Write
Sequential Read Sequential Write

On the longer synthetic tests that bring in some slightly higher queue depths, the improved random read performance of the 870 EVO is a bit more clear. In one sense it is impressive to see Samsung squeeze a bit more performance out of the same SATA bottleneck, but we're still talking about small incremental refinements where NVMe enables drastic improvements. Aside from random reads, the 870 EVO's performance improvements are exceedingly minute and it should be considered essentially tied with most other recent mainstream TLC SATA drives.

Sustained IO Performance
Random Read Random Write
Sequential Read Sequential Write

Power consumption is one area where Samsung could theoretically offer more significant improvements despite still being constrained by the same SATA interface, but the 870 EVO doesn't really deliver any meaningful improvements there. The 4TB model is consistently a bit less efficient than the 1TB model on account of having more memory to keep powered up, but when comparing the 1TB model against its predecessor and competing drives there's nothing particularly noteworthy about the 870 EVO. SK hynix's Gold S31 has a modest efficiency advantage for random IO while Samsung is technically the most efficient of these SATA drives for sequential IO.

Random Read
Random Write
Sequential Read
Sequential Write

The queue depth scaling behavior of the 870 EVOs is almost identical to the 860 EVOs and still quite typical for mainstream SATA drives. For random reads the 870 EVOs saturate around QD16, while for random writes QD4 suffices. On the sequential IO tests there's only a small performance gain from QD1 to QD16, and the more interesting question is how stable performance is through the rest of the sequential tests. The 1TB 870 EVO seems to run out of SLC cache a bit earlier than the 860 EVO when the sequential write test is running on an 80% full drive, but the 4TB model has plenty of cache to finish out that test at full speed.

Random Read Performance Consistency

This test illustrates how drives with higher throughput don't always offer better IO latency and Quality of Service (QoS), and that latency often gets much worse when a drive is pushed to its limits. This test is more intense than real-world consumer workloads and the results can be a bit noisy, but large differences that show up clearly on a log scale plot are meaningful. For more details, please see the overview of our 2021 Consumer SSD Benchmark Suite.

Consistent with most of our other read performance tests, the Samsung 870 EVO shows slightly better average and 99th percentile random read latencies than most of its SATA competition. Even some of the entry-level NVMe drives that can deliver higher random read throughput than is possible for the 870 EVO still have clearly higher latency across most or all of the throughput range that the 870 EVO can cover. A QLC-based or DRAMless TLC NVMe SSD can potentially offer far higher throughput than any SATA SSD, but clearly beating the 870 EVO on both throughput and latency requires stepping up to a more mainstream NVMe design with DRAM and TLC NAND.

Trace Tests: AnandTech Storage Bench and PCMark 10 Advanced Synthetic Tests: Block Sizes and Cache Size Effects
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  • flyingpants265 - Thursday, February 18, 2021 - link

    SSDs can do 3000mb/s or a lot more with parallelization and raid, you could probably get 30,000mb/s or some insane number like that, eventually with a single SSD.

    It's a little weird that we don't have better cables.
    Reply
  • Great_Scott - Thursday, February 18, 2021 - link

    It's interesting to see the SATA market deteriorate.

    I don't understand how most PCs can get away with two or one physical drive slots, but assuming that remains the trend, I wonder what NAS owners are going to do once SSDs are cheap and large enough to use for RAID but there aren't any products to use for it...
    Reply
  • mooninite - Wednesday, February 17, 2021 - link

    Why should rotating rust drives still be shipped with 512e sectors?

    It must be the same marketing data these manufacturers are using to show they still need to make SATA SSDs.
    Reply
  • PixyMisa - Wednesday, February 17, 2021 - link

    Time to start replacing SATA with USB-C. Reply
  • eek2121 - Wednesday, February 17, 2021 - link

    In the past I have advocated for internal USB-C because it would be a perfect replacement for SATA. Reply
  • futrtrubl - Wednesday, February 17, 2021 - link

    Way back when there was even an HDD that was natively usb, the Samsung Spinpoint N3U Reply
  • Jorgp2 - Wednesday, February 17, 2021 - link

    Lol.

    It's slower than SATA
    Reply
  • Krimzon - Wednesday, February 17, 2021 - link

    How is 40gbps slower than 6? Reply
  • futrtrubl - Wednesday, February 17, 2021 - link

    Hell, USB 3.1 (SuperSpeed+/3.2 gen2x1/3.2 gen1x2) is faster than SATA Reply
  • Beaver M. - Wednesday, February 17, 2021 - link

    I think USB latency is much higher. Not sure, though. Reply

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