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

The random read performance from the SLC caches on the Rocket Q4 and MP600 CORE are plenty fast, albeit still not able to match the Intel SSD 670p. Outside the cache, the two Phison E16 QLC drives are definitely slower than mainstream TLC drives, but their performance is fine by QLC standards.

For short bursts of writes that don't overflow the SLC cache, these drives are very fast and their caches are still useful even when the drive as a whole is 80% full.

As is often the case for Phison-based drives, the low queue depth sequential read performance is still not great, but sequential writes are very fast and do reach PCIe Gen4 speeds.

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 Throughput Power Efficiency
Random Write Throughput Power Efficiency
Sequential Read Throughput Power Efficiency
Sequential Write Throughput Power Efficiency

The random read performance from the Rocket Q4 and MP600 CORE is greatly improved over the earlier Phison E12 QLC SSDs, at least when the test is hitting a narrow slice of the drive that should be entirely within the SLC cache. Random and sequential write results are both decent given that these are in many ways still low-end drives. These two drives are large enough (and have enough SLC cache) to handle much larger bursts of writes than 1TB models, even when the drives are 80% full.

Random Read
Random Write
Sequential Read
Sequential Write

The E16-based QLC drives are able to continue scaling up random read throughput (from the SLC cache, at least) long past the points where other QLC drives hit a performance wall. The 4TB Rocket Q4 scales better than the 2TB MP600 CORE, and by QD128 it is handling random reads at 2.5GB/s and still has headroom for more performance. For random writes, the Rocket Q4 and MP600 CORE saturate around QD4 or a bit later, which is fairly typical behavior.

When testing sequential reads, we get the characteristic behavior from Phison controllers: poor throughput until around QD16 or so, at which point there's enough data in flight at any given time to allow the SSD controller to stay properly busy. The sequential write results are messy since both drives run out of SLC cache frequently during this test, and that makes it hard to identify what the performance limits would be in more favorable conditions. But it appears that sequential write speed is saturating around QD2, and stays flat with increasing queue depth except when the caching troubles come up.

Random Read Latency

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.

The Sabrent Rocket Q4 and Corsair MP660 CORE show better latency on this test than the other low-end NVMe drives, but all the mainstream TLC drives with DRAM have clear advantages. Even the Samsung 870 EVO has lower latency until it gets close to saturating the SATA link. Between the 2TB MP600 CORE and the 4TB Rocket Q4, the larger drive unsurprisingly can sustain higher random read throughput and its latency climbs more gradually, but the Rocket Q4 does have more transient latency spikes along the way.

Trace Tests: AnandTech Storage Bench and PCMark 10 Advanced Synthetic Tests: Block Sizes and Cache Size Effects
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  • cyrusfox - Friday, April 9, 2021 - link

    Great write up, unfortunate endurance regression (Went from 260 down to 225 cycles), seems only Intel is pushing QLC higher on endurance (200 to 300 to 370 cycles). Impressive random performance though, odd that only Intel appears to be extracting higher endurance with each new gen of QLC though.
  • Samus - Sunday, April 11, 2021 - link

    I noticed that in the 670p review and I'm glad someone pointed it out. I'd like to know if it's a programming\firmware logic thing that extracts better endurance through creative block wear leveling, reduced write amplification (perhaps delayed garbage collection and stuff) or they have more spare area? It's hard to believe they have superior manufacturing compared to "everyone" but maybe they do...
  • Oxford Guy - Sunday, April 11, 2021 - link

    Creativity isn't going to change the fact that there are twice as many voltage states in QLC vs. TLC.
  • cyrusfox - Sunday, April 11, 2021 - link

    With PLC on the horizon, QLC is going to look incredible by comparison :)
    I wonder what the internal goal is to make PLC viable, 70Cycles, 100 cycles? @ 32 Threshold charge states will be an engineering feat all on its own, Impressive QLC is able to function to nearly 400 cycles with 16 separate states(How much are they overprovisioned?).
    From what I see in drive warranties based on underlying nand cells, we see around a 1/4 reduction in endurance/cycles each time they increase the bits per cell (10k,2k,400-1.2K,100-375,20-100). QLC is about 4 years old now with mass market release 3 years ago. PLC is definitely on the near horizon.
  • James5mith - Friday, April 9, 2021 - link

    For the minimal price increase, get the E18 based Sabrent Rocket 4 Plus 4TB model. https://www.amazon.com/dp/B08VF99PV8/
  • HideOut - Friday, April 9, 2021 - link

    Thats still a big price increase. More than $150 even on sale.
  • TheinsanegamerN - Saturday, April 10, 2021 - link

    With far better long term write endurance, write speed, ece. QLC has a nasty habit of slowing WAY down once filled up.
  • Oxford Guy - Sunday, April 11, 2021 - link

    It shows its true performance.

    Once the 'SLC' disguise is gone...
  • wr3zzz - Friday, April 9, 2021 - link

    I don't know why SN550 was used in the performance benchmarks when these QLC drives are priced at premium to SN750.
  • sjkpublic@gmail.com - Friday, April 9, 2021 - link

    For QLC write endurance I look at 600 x size. The numbers here are rather poor. Maybe its a mistake?

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