New NAND Storage Development: SLC, MLC, TLC, QLC NAND ... going for PLC
NAND flash memory products have seen many stages of development and are evolving continuously. SLC is very expensive, MLC as well, TLC currently is the sweet spot and yes, this year we've already reviewed the QLC based NAND products.
That combined with more layers per package increase storage volumes and lower prices. Each time you step it down a notch (adding more bits to write in one cell), you'll lose a number of write cycles but also it will have an effect on performance. Toshiba is trying the next step, after QLC they are developing and researching PLC. PLC and is short for Penta level cell and the technology would store five bits per cell.
The word is out at Toshiba and WD (Sandisk) they already have working prototypes. it remains to be seen if this tech will actually make it to viable production lines, as it is increasingly more complex. PLC would require 32 different types of voltage.
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If it means I can get a 4TB games SSD for ~$150 I’m all for it.
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Development of new technologies is always welcomed.
That said, I hate the reliability of QLC and much rather stick to TLC. I can't imagine the endurance PLC will have...
I'm sure that with help from development of PLC, QLC will get better reliability. But there's a point that I'd rather my drive live for longer than having more density.
My current Crucial MX100 256GB drive has 5 years and still going strong. I'm upgrading to NVMe but this drive will live on my old mom's computer to keep working.
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if we look at this, basically nand maker somewhat "fooling-around"
at beginning SLC - high-durability / expensive, so to push price lower, they make QLC/PLC - low-durability / much cheaper
luckily the nand capacity become so big, basically it cover-up the cons that qlc/plc have which is low write amplification, and as most user wont full-up their storage having free-space also help
SLC = 100K P/E cycles
MLC = 10K P/E cycles
TLC = 3K P/E cycles which i still think sweet-spot
QLC = 1K P/E cycles
PLC = 300 P/E cycles?
even SSD-maker using SLC cache system, far-better controller etc.
if we keep going on this trend, somewhat it make me think, probably the future SSD durability wont be much different than traditional HDD, especially in write-intensive environment
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Usually you have most drives starting to have issues with non-nand related stuff (controller etc), and around 1 out of 4 drive (of the same type)
will have nand related problems after a few years, so it might work for most consumers (especially at lower price),
but when i saw that the sustained TLC numbers on a nvme get beaten by an older MLC drive running sata,
yeah, i wont get anything "after" TLC.
even switched back to MLC for one of my backup drives i replaced, just to make sure.
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Wonder how many layers they can get this down to before reliability and the hardware's overall lifetime is reduced too badly, Penta(gram) layer SSD now and next up I suppose is hexa, whatever seven is called and then octa if this keeps going on.
Then again really long huge numbers shrinking doesn't really say much either, hardware dies whenever the user is most inconvenienced by it as per some law from how the universe just works and that's that. :p
Suppose storage capacity and affordability can continue to go up too, just have to monitor overall status and keep the priority files backed up and that should be good enough.
EDIT: As for regular usage I'm pretty sure 3 - 5 years is still more than feasible same as the general lifetime for a HDD before they start showing signs and even then it can last quite a while plus no mechanical parts in a SSD and it can theoretically keep going even more removing that little wear and tear and other issues with spinning headers and platters even if the memory cells have a finite lifetime but tech keeps it optimum so it gets a lot of lifetime regardless of some arbitrary number of hours.