Final Words & Conclusion

Final Words

We feel that QLC still needs to be a notch cheaper in order to become attractive enough. This 2TB unit still sits at 315 USD/EUR meaning that 16 cents per GB marker. QLC needs to be at 10 cents per GB in my belief. The problem sits in the fact that QLC often reveals large write holes, the manufacturers need to solve that, and as such need to add a Pseudo SLC cache and ... expensive DRAM. This 2TB SSD has a whopping 1 GB DRAM cache, and that does add to the bill of materials alright. 

Performance

With the buffers in place, QLC write holes are a thing of the past though, I mean this is a REALLY properly performing SSD. This little puppy reads and writes full speed all the time. The overall throughput of the NVMe SSD is splendid; it will not hit that TLC/QLC write hole and thus overall is a strong contender offering all the perf you need really. NVMe based M.2. have been growing and advancing in performance really fast with NAND; combine it with a proper controller, and you can get proper performance; this SSD averages out incredibly well. The Vertically stacked QLC written NAND combined with the Phison 5012-E12S controller and suitable workloads reveals close to 2 GB/s to 3 GB/sec in writes. 

Endurance

The other reality is that QLC is not cherished for its lower endurance. However, with substantial storage volumes, that's far less of an issue as there are more NAND cells to be written. That's 530 TBW for the tested 2 TB unit. If you would write a massive 50GB per day all days of the year, then you are looking at almost 29 years of lifespan (for the 2 TB model). That's 13 years for the 1TB model and 6.5 years for the 500 GB model. That last one is a bit icky, but again my example is 50GB written each day and all days of the year, which is incomparably more than your average workload reality in writing. Silicon Power is feeling really confident about these values and offers a 5-year warranty to go along with it. 

Concluding

If QLC NAND prices would come down a little bit more then I would wholeheartedly recommend them. However, I'd steer you to the bigger TB volume sizes just for endurance alone. Used for a lot of cold storage (not constantly writing files) this SSD however is offering staggering performance for something QLC. To be able to accomplish that, Silicon power needs a big pSLC cache as well as 2 GB of DRAM, however that combo works extremely well as we have not been able to notice any viable write holes. And we tested that up-to 110 GB continuously written with a full hardcore load. Summed up, the UD70 manages to make me think differently about QLC NAND. When volume goes up, you have more NAND cells available, which prolongs your endurance massively. When one can eliminate the QLC write hole, then there's little left to be worried about. SP back this up with a 5-year warranty on this series, 5-years or the TBW value reached, whichever one comes first. However, that last bit remains a culprit, as TLC based NAND NVMe SSD do offer more or less the same at similar prices. I think once we reach 10 cents per GB, say 225 EUR for an SSD like this, that's where the industry will hit a sweet spot. None the less I was impressed about sheer performance, and as such the SSD absolutely comes approved by us.

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