QLC Goes To 8TB: Samsung 870 QVO and Sabrent Rocket Q 8TB SSDs Reviewed
by Billy Tallis on December 4, 2020 8:00 AM ESTAnandTech Storage Bench - The Destroyer
The Destroyer is an extremely long test replicating the access patterns of very IO-intensive desktop usage. A detailed breakdown can be found in this article. Like real-world usage, the drives do get the occasional break that allows for some background garbage collection and flushing caches, but those idle times are limited to 25ms so that it doesn't take all week to run the test. These AnandTech Storage Bench (ATSB) tests do not involve running the actual applications that generated the workloads, so the scores are relatively insensitive to changes in CPU performance and RAM from our new testbed, but the jump to a newer version of Windows and the newer storage drivers can have an impact.
We quantify performance on this test by reporting the drive's average data throughput, the average latency of the I/O operations, and the total energy used by the drive over the course of the test.
Average Data Rate | |||||||||
Average Latency | Average Read Latency | Average Write Latency | |||||||
99th Percentile Latency | 99th Percentile Read Latency | 99th Percentile Write Latency | |||||||
Energy Usage |
The Sabrent Rocket Q turns in shockingly good scores on The Destroyer, matching the Samsung 970 EVO Plus, a high-end TLC SSD. The reason why the decidedly less high-end Rocket Q can do this is due entirely to the extreme capacity. For the first time, we have a drive that can handle The Destroyer entirely in its SLC cache. That means the results here are a bit misleading, as the drive would not be able to sustain this level of performance if it was full enough to reduce the SLC cache capacity down to more typical sizes. Power efficiency is also pretty decent here, but again operating out of the SLC cache helps.
Meanwhile, the 8TB Samsung 870 QVO turns in pretty much the same performance scores as the 4TB model, as expected. However, the 8TB drive is a little bit more power-hungry due to the higher part count.
AnandTech Storage Bench - Heavy
Our Heavy storage benchmark is proportionally more write-heavy than The Destroyer, but much shorter overall. The total writes in the Heavy test aren't enough to fill the drive, so performance never drops down to steady state. This test is far more representative of a power user's day to day usage, and is heavily influenced by the drive's peak performance. The Heavy workload test details can be found here. This test is run twice, once on a freshly erased drive and once after filling the drive with sequential writes.
Average Data Rate | |||||||||
Average Latency | Average Read Latency | Average Write Latency | |||||||
99th Percentile Latency | 99th Percentile Read Latency | 99th Percentile Write Latency | |||||||
Energy Usage |
The Heavy test doesn't allow the Sabrent Rocket Q a unique advantage from its massive SLC cache; the smaller high-end NVMe drives can also make good use of their caches and overtake the Rocket Q's performance. However, it does appear that the sheer capacity of the 8TB Rocket Q continues to help significantly on the full-drive test runs. We haven't measured it directly, but I suspect the minimum SLC cache size reached when the drive is full is still quite a bit larger than what the 2TB and smaller drives have to work with, and that's how the Rocket Q avoids the horrible latency spikes that the other QLC drives suffer from.
As on The Destroyer, the 8TB Samsung 870 QVO shows no major differences in performance or efficiency from the 4TB model, which means it's still clearly a bit on the slow side even by SATA standards—especially when full.
AnandTech Storage Bench - Light
Our Light storage test has relatively more sequential accesses and lower queue depths than The Destroyer or the Heavy test, and it's by far the shortest test overall. It's based largely on applications that aren't highly dependent on storage performance, so this is a test more of application launch times and file load times. This test can be seen as the sum of all the little delays in daily usage, but with the idle times trimmed to 25ms it takes less than half an hour to run. Details of the Light test can be found here. As with the ATSB Heavy test, this test is run with the drive both freshly erased and empty, and after filling the drive with sequential writes.
Average Data Rate | |||||||||
Average Latency | Average Read Latency | Average Write Latency | |||||||
99th Percentile Latency | 99th Percentile Read Latency | 99th Percentile Write Latency | |||||||
Energy Usage |
The 8TB Sabrent Rocket Q offers decent performance on the Light test, even when full: it still provides a large enough SLC cache to handle all the writes from this test. A lot of smaller drives (using QLC or TLC) can't manage that and show greatly increased write latency on the full-drive test runs.
The 8TB Samsung 870 QVO shows slightly improved latency scores on the full-drive test run compared to the 4TB model, but otherwise performance is the same as expected. As usual, the 8TB QVO is a bit more power-hungry than the smaller versions, and the Rocket Q is considerably more power-hungry than the smaller low-end NVMe drives.
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shelbystripes - Thursday, December 10, 2020 - link
Dude, you don't seem to understand how "consumerist capitalism" DOES work. QLC will still be more than good enough for most consumers, or at least, that's what manufacturers are banking on. They still need to sell the hardware, and they're competing in a world where MLC and TLC SSDs still widely exist.The only way to get there will be lower cost... and there will be plenty of consumers who respond to high-capacity QLC SSDs at lower costs than "scale" alone can achieve for MLC or TLC drives, and who won't care about the drop in MTBF because QLC SSDs still have more total writes than they'll ever need. QLC SSDs aren't going to be for everyone, but if TLC (even 3D TLC) is such cheap technology that "scale" is all you need to hit 8TB SSDs with it, why isn't anyone making sub-$1K 8TB 3D TLC drives and competing with these? Shouldn't they be?
You just don't know what you're talking about, yet you have the arrogance of someone prepared to speak for everybody uniformly.
boozed - Saturday, December 5, 2020 - link
The Sabrent appears to perform quite well in real world tests, regardless of its synthetic/theoretical performance. Is this a bad thing?Hixbot - Saturday, December 5, 2020 - link
MLC/TLC is still available at extra cost. Meanwhile QLC is pushing HDDs out of the market.Oxford Guy - Sunday, December 6, 2020 - link
"MLC/TLC is still available at extra cost."Economy of scale. QLC is an attack on TLC and MLC.
Oxford Guy - Sunday, December 6, 2020 - link
Also the article says:"QLC NAND offers just a 33% increase in theoretical storage density, but in practice most QLC NAND is manufactured as 1024Gbit dies while TLC NAND is manufactured as 256Gbit and 512Gbit dies."
Which means manufacturers are trying to kneecap TLC to push QLC.
Spunjji - Monday, December 7, 2020 - link
Or it means that manufacturing TLC at those capacities per die would result in a bloated die size with decreased yields, increased costs, and too-few dies per drive to reach competitive speeds at the most common capacities.The problem with having a conclusion and looking for evidence to support it is that you can come up with all sorts of silly reasons for things that are perfectly explicable by other means.
Oxford Guy - Thursday, December 10, 2020 - link
Speculativeshelbystripes - Thursday, December 10, 2020 - link
It's ironic that you respond to someone calling out your unsubstantiated speculation as "speculative". If you're opposed to speculation, you should retract your statements assuming that manufacturers are out to "kneecap" MLC/TLC like they have some secret agenda against higher-reliability parts...Spunjji - Monday, December 7, 2020 - link
Do you have any evidence that would support that claim? Say, TLC costs rising even as QLC rolls out, in a way that doesn't reflect the usual industry supply/demand fluctations?Oxford Guy - Thursday, December 10, 2020 - link
Yes. The die sizes offered with TLC are 50% smaller at best. That magnifies the 30% density increase of QLC automatically. Maybe this reply will stick. Here’s to hoping.