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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Oxford Guy - Monday, December 7, 2020 - link
I have three OCZ 240 GB Vertex 2 drives. They're all bricked. Two of them were replacements for bricked drives. One of them bricked within 24 hours of being used. They bricked in four different machines.Pure garbage. OCZ pulled a bait and switch, where it substituted 64-bit NAND for the 32-bit the drives were reviewed/tested with and rated for on the box. The horrendously bad Sandforce controller choked on 64-bit NAND and OCZ never stabilized it with its plethora of firmware spew. The company also didn't include the 240 GB model in its later exchange program even though it was the most expensive in the lineup. Sandforce was more interested in protecting the secrets of its garbage design than protecting users from data loss so the drives would brick as soon as the tiniest problem was encountered and no tool was ever released to the public to retrieve the data. It was designed to make that impossible for anyone who wasn't in spycraft/forensics or working for a costly drive recovery service. I think there was even an announced partnership between OCZ and a drive recovery company for Sandforce drives which isn't at all suspicious.
Oxford Guy - Monday, December 7, 2020 - link
The Sandforce controller also was apparently incompatible with the TRIM command but customers were never warned about that. So, TRIM didn't cause performance to rebound as it should.UltraWide - Saturday, December 5, 2020 - link
AMEN for silence. I have a 6 x 8TB NAS and even with 5,400rpm hdds it's quite loud.TheinsanegamerN - Saturday, December 5, 2020 - link
I really want to like the slim, and would love one that I could load up with 2TB SATA SSDS in raid, but they've drug their feet on a 10G version. 1G or even 2.5G is totally pointless for SSD NASes.bsd228 - Friday, December 4, 2020 - link
sequential transfer speed isn't all that matters.two mirrored SSDs on a 10G connection can get you better read performance than any SATA ssd locally. But it can be shared across all of the home network.
david87600 - Friday, December 4, 2020 - link
My thoughts exactly. SSD rarely makes sense for NAS.Hulk - Friday, December 4, 2020 - link
What do we know about the long term data retention of these QLC storage devices?Oxford Guy - Friday, December 4, 2020 - link
16 voltage states to deal with for QLC. 8 voltage states for TLC. 4 for 2-layer MLC. 2 for SLC.More voltage states = bad. The only good thing about QLC is density. Everything else is worse.
Spunjji - Monday, December 7, 2020 - link
It's not entirely. More voltage states is more difficult to read, for sure, but they've also begun implementing more robust ECC systems with each new variant of NAND to counteract that.I'd trust one of these QLC drives more than I'd trust my old 120GB 840 drive in that regard.
Oxford Guy - Tuesday, December 8, 2020 - link
Apples and oranges. More robust things to try to work around shortcomings are not the shortcomings not existing.