For the same price, you can get twice the space for 1/4 the endurance, thrice the space for 1/8th the endurance, and now four times the space for 1/16th the endurance. Most people don't realise that is a horrible tradeoff, because NAND flash marketing and terminology like "TLC" or "QLC" is intentionally deceptive and manufacturers have been very secretive about the true endurance specifications, as well as trying to overprice SLC out of production. If more people knew the truth of what they were trying to do, we wouldn't be in this situation.
> as well as trying to overprice SLC out of production.
Is it even possible to buy SLC drives any more? For the past 5+ years the only outlet I've been able to find that even advertise SLC is https://www.delkin.com/, and you need to speak to sales to even get a price. I just assumed they and any other similar suppliers bought giant lots of chips at the tail end of SLC production and jack up the price on every new order as their supply dwindles. Or maybe they cobble together drives from the tiny SLC chips used for cache on modern SSDs?
Yes, small ones for industrial use. They're extremely expensive, however.
Looking at the raw NAND flash prices, SLC seems to still be around $4.60USD/GB, or roughly the same as it was over a decade ago, while MLC is already <$1USD/GB despite only a doubling in capacity. TLC and QLC seems to be down in the $0.10USD/GB. You can still buy raw SLC NAND flash in the smaller capacities of few GBs; this one is only 512MB, at the price mentioned above:
Enmotus partnered with Phison to produce a QLC SSD that mapped the first several GB of logical blocks to SLC. This was sold bundled with Enmotus's SSD caching software, but it could also be treated as simply having a SLC partition and a QLC partition that are largely independent.
Samsung 980 Pro, the original, does that when sufficiently empty, to offer around iirc 10% nominal capacity of SLC-mode write buffer (given they are TLC, that would be around 30% of the NAND).
Many TLC drives have SLC cache so if you limit usage of the drive you may effectively use it in SLC-only mode. This does not say anything about its endurance however. If you want endurance, better mirror your data to HDD.
Show me software that can mirror an SSD to HDD in realtime without the "backup" being affected by the slower write speeds. I was looking for a way to do this a few years ago, and couldn't find anything. I'd be very happy if I could pull my SSD out, change my boot drive, and boot into my existing OS without any issues. My understanding is that existing solutions for this delay write confirmation until both drives are complete, negating the speed advantage of the SSD.
Check out Syncthing. I personally run two instances of syncthing, synchronization happens very fast and as long as there isn't high write volumes it syncs pretty quickly. If you don't need realtime backup, rsync'ing in a loop would work.
If you want to use a drive as pure SLC, you're probably better off buying a QLC drive than a TLC drive. QLC drives are more reliant on SLC caching and tend to be more reluctant to migrate data from SLC to QLC when it isn't absolutely necessary.
For most people this isn't a horrible tradeoff. For example, my desktop which I use pretty heavily, I've averaged 24 GB writes per day. With 500 drive writes of a TLC drive, my ssd will last me roughly 50 years at current rate. If I had to chose between a 300 GB SSD that will last me 400 years or a 1TB ssd that lasts 50 years, I'll take the TB one any day of the week.
While NAND endurance has certainly gone down, FTLs got much better during the same time so that SSD endurance is still fine for most people. And if the stock endurance isn't enough, a little overprovisioning is probably better than dropping back to very expensive MLC.
